{
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            "opera": "mirror",
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            "web-features:snapshot:ecmascript-1",
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            "safari_ios": "mirror",
            "samsunginternet_android": "mirror",
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            "webview_ios": "mirror"
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          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/break",
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            "web-features:snapshot:ecmascript-1",
            "web-features:javascript"
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            "chrome_android": "mirror",
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              "version_added": "1"
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            "safari_ios": "mirror",
            "samsunginternet_android": "mirror",
            "webview_android": "mirror",
            "webview_ios": "mirror"
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            "deprecated": false
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          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/class",
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                "notes": "Strict mode is required."
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            "opera": "mirror",
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            "samsunginternet_android": "mirror",
            "webview_android": "mirror",
            "webview_ios": "mirror"
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            "experimental": false,
            "standard_track": true,
            "deprecated": false
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        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/const",
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            "chrome_android": "mirror",
            "deno": {
              "version_added": "1.0"
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            "edge": {
              "version_added": "12"
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            "firefox": {
              "version_added": "36",
              "notes": [
                "Before Firefox 13, `const` is implemented, but re-assignment is not failing.",
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            "firefox_android": "mirror",
            "ie": {
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              "version_added": "10.1"
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              "version_added": "5.1"
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            "safari_ios": "mirror",
            "samsunginternet_android": "mirror",
            "webview_android": "mirror",
            "webview_ios": "mirror"
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          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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      "continue": {
        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/continue",
          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-continue-statement",
          "tags": [
            "web-features:snapshot:ecmascript-1",
            "web-features:javascript"
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          "support": {
            "chrome": {
              "version_added": "1"
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            "chrome_android": "mirror",
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              "version_added": "1.0"
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            "edge": {
              "version_added": "12"
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              "version_added": "1"
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              "version_added": "3"
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            "oculus": "mirror",
            "opera": {
              "version_added": "4"
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            "opera_android": {
              "version_added": "10.1"
            },
            "safari": {
              "version_added": "1"
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            "safari_ios": "mirror",
            "samsunginternet_android": "mirror",
            "webview_android": "mirror",
            "webview_ios": "mirror"
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          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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      "debugger": {
        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/debugger",
          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-debugger-statement",
          "tags": [
            "web-features:javascript"
          ],
          "support": {
            "chrome": {
              "version_added": "5"
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            "edge": {
              "version_added": "12"
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              "version_added": "1"
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              "version_added": "4"
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            "nodejs": {
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            "oculus": "mirror",
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              "version_added": "10"
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              "version_added": "10.1"
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            "safari": {
              "version_added": "5"
            },
            "safari_ios": "mirror",
            "samsunginternet_android": "mirror",
            "webview_android": "mirror",
            "webview_ios": "mirror"
          },
          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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        }
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      "do_while": {
        "__compat": {
          "description": "`do...while`",
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/do...while",
          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-do-while-statement",
          "tags": [
            "web-features:snapshot:ecmascript-3",
            "web-features:javascript"
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          "support": {
            "chrome": {
              "version_added": "1"
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            "chrome_android": "mirror",
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            "firefox": {
              "version_added": "1"
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            "nodejs": {
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            "opera_android": {
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              "version_added": "1"
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            "safari_ios": "mirror",
            "samsunginternet_android": "mirror",
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          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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          "description": "Empty statement (`;`)",
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/Empty",
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          "tags": [
            "web-features:snapshot:ecmascript-1",
            "web-features:javascript"
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          "support": {
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              "version_added": "3"
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            "chrome_android": "mirror",
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            "oculus": "mirror",
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              "version_added": "3"
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            "opera_android": {
              "version_added": "10.1"
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            "safari": {
              "version_added": "5"
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            "safari_ios": "mirror",
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            "webview_android": "mirror",
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          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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      "export": {
        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/export",
          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-scripts-and-modules.html#sec-exports",
          "tags": [
            "web-features:js-modules"
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          "support": {
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              "version_added": "61"
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            "oculus": "mirror",
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              "oculus": "mirror",
              "opera": "mirror",
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              "standard_track": true,
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                "version_added": "72"
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              "chrome_android": "mirror",
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              "oculus": "mirror",
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          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-for-statement",
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          "description": "`for await...of`",
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/for-await...of",
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            "standard_track": true,
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            "tags": [
              "web-features:snapshot:ecmascript-2018",
              "web-features:async-iterators"
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              "chrome": {
                "version_added": "63"
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              "chrome_android": "mirror",
              "deno": {
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              "edge": {
                "version_added": "12"
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              "firefox": {
                "version_added": "57"
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              "firefox_android": "mirror",
              "ie": {
                "version_added": false
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              "nodejs": {
                "version_added": "10.0.0"
              },
              "oculus": "mirror",
              "opera": "mirror",
              "opera_android": "mirror",
              "safari": {
                "version_added": "7"
              },
              "safari_ios": "mirror",
              "samsunginternet_android": "mirror",
              "webview_android": "mirror",
              "webview_ios": "mirror"
            },
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            "tags": [
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              "chrome": {
                "version_added": "51"
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              "chrome_android": "mirror",
              "deno": {
                "version_added": "1.0"
              },
              "edge": {
                "version_added": "14"
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              "firefox": {
                "version_added": "53"
              },
              "firefox_android": "mirror",
              "ie": {
                "version_added": false
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              "nodejs": {
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              "oculus": "mirror",
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                "version_added": "7"
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          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function",
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            "description": "Trailing comma in parameters",
            "tags": [
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              "chrome": {
                "version_added": "58"
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              "chrome_android": "mirror",
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                "version_added": "1.0"
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              "edge": {
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            "status": {
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          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function*",
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          "tags": [
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              "version_added": "39"
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            "description": "`IteratorResult` object instead of throwing",
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              "chrome": {
                "version_added": "49"
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                "version_added": "13"
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              "firefox": {
                "version_added": "29"
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              "oculus": "mirror",
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              "safari": {
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            "status": {
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              "standard_track": true,
              "deprecated": false
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          }
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            "description": "Not constructable with `new` (ES2016)",
            "tags": [
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            "support": {
              "chrome": {
                "version_added": "50"
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              "deno": {
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                "version_added": "43"
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              "opera": "mirror",
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            "status": {
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              "deprecated": false
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        "trailing_comma_in_parameters": {
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            "description": "Trailing comma in parameters",
            "tags": [
              "web-features:generators"
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            "support": {
              "chrome": {
                "version_added": "58"
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              "deno": {
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                "version_added": "52"
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              "oculus": "mirror",
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            "status": {
              "experimental": false,
              "standard_track": true,
              "deprecated": false
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          "description": "`if...else`",
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/if...else",
          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-if-statement",
          "tags": [
            "web-features:snapshot:ecmascript-1",
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          "support": {
            "chrome": {
              "version_added": "1"
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            "chrome_android": "mirror",
            "deno": {
              "version_added": "1.0"
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            "edge": {
              "version_added": "12"
            },
            "firefox": {
              "version_added": "1"
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            "firefox_android": "mirror",
            "ie": {
              "version_added": "3"
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            "nodejs": {
              "version_added": "0.10.0"
            },
            "oculus": "mirror",
            "opera": {
              "version_added": "3"
            },
            "opera_android": {
              "version_added": "10.1"
            },
            "safari": {
              "version_added": "1"
            },
            "safari_ios": "mirror",
            "samsunginternet_android": "mirror",
            "webview_android": "mirror",
            "webview_ios": "mirror"
          },
          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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        }
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      "import": {
        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/import",
          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-scripts-and-modules.html#sec-imports",
          "tags": [
            "web-features:js-modules"
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          "support": {
            "chrome": {
              "version_added": "61"
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            "chrome_android": "mirror",
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              "version_added": "1.0"
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            "edge": {
              "version_added": "16"
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            "firefox": {
              "version_added": "60"
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            "firefox_android": "mirror",
            "ie": {
              "version_added": false
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            "nodejs": [
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                "version_added": "13.2.0",
                "notes": "Modules must either have a filename ending in `.mjs`, or the nearest parent `package.json` file must contain `\"type\": \"module\"`. See Node's [ECMAScript Modules documentation](https://nodejs.org/api/esm.html#esm_enabling) for more details."
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            "opera": "mirror",
            "opera_android": "mirror",
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            "webview_android": "mirror",
            "webview_ios": "mirror"
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          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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            "description": "Available in workers",
            "tags": [
              "web-features:js-modules-workers"
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            "support": {
              "chrome": {
                "version_added": "80"
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              "deno": {
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              "edge": "mirror",
              "firefox": {
                "version_added": "114"
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              "firefox_android": "mirror",
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              "oculus": "mirror",
              "opera": "mirror",
              "opera_android": "mirror",
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                "version_added": "15"
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              "safari_ios": "mirror",
              "samsunginternet_android": "mirror",
              "webview_android": "mirror",
              "webview_ios": "mirror"
            },
            "status": {
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              "standard_track": true,
              "deprecated": false
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            "description": "Import attributes with `assert` syntax (formerly import assertions)",
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              "chrome": {
                "version_added": "91",
                "version_removed": "126"
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              "chrome_android": "mirror",
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              "edge": "mirror",
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              "opera": {
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                "version_added": false
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              "safari": {
                "version_added": false
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              "safari_ios": "mirror",
              "samsunginternet_android": "mirror",
              "webview_android": "mirror",
              "webview_ios": "mirror"
            },
            "status": {
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              "standard_track": false,
              "deprecated": true
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            "__compat": {
              "description": "`assert {type: 'css'}`",
              "support": {
                "chrome": {
                  "version_added": "93",
                  "version_removed": "126"
                },
                "chrome_android": "mirror",
                "deno": {
                  "version_added": false
                },
                "edge": "mirror",
                "firefox": {
                  "version_added": false,
                  "impl_url": "https://bugzil.la/1720570"
                },
                "firefox_android": "mirror",
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                  "version_added": false
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                "nodejs": {
                  "version_added": false
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                "oculus": "mirror",
                "opera": {
                  "version_added": false
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                "opera_android": {
                  "version_added": false
                },
                "safari": {
                  "version_added": false,
                  "impl_url": "https://webkit.org/b/227967"
                },
                "safari_ios": "mirror",
                "samsunginternet_android": "mirror",
                "webview_android": "mirror",
                "webview_ios": "mirror"
              },
              "status": {
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                "standard_track": false,
                "deprecated": true
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              "description": "`assert {type: 'json'}`",
              "support": {
                "chrome": {
                  "version_added": "91",
                  "version_removed": "126"
                },
                "chrome_android": "mirror",
                "deno": {
                  "version_added": "1.17"
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                "edge": "mirror",
                "firefox": {
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                "firefox_android": "mirror",
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                    "version_removed": "22.0.0"
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                    "version_added": "16.15.0",
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                "oculus": "mirror",
                "opera": {
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                "opera_android": {
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                "safari": {
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                "safari_ios": "mirror",
                "samsunginternet_android": "mirror",
                "webview_android": "mirror",
                "webview_ios": "mirror"
              },
              "status": {
                "experimental": false,
                "standard_track": false,
                "deprecated": true
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            }
          }
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            "description": "Import attributes (`with` syntax)",
            "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/import/with",
            "spec_url": "https://tc39.es/proposal-import-attributes/#prod-WithClause",
            "support": {
              "chrome": {
                "version_added": "123"
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              "chrome_android": "mirror",
              "deno": {
                "version_added": "1.37"
              },
              "edge": "mirror",
              "firefox": {
                "version_added": false,
                "impl_url": "https://bugzil.la/1736059"
              },
              "firefox_android": "mirror",
              "ie": {
                "version_added": false
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              "nodejs": [
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                  "version_added": "20.10.0"
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                {
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              ],
              "oculus": "mirror",
              "opera": "mirror",
              "opera_android": "mirror",
              "safari": {
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              "safari_ios": "mirror",
              "samsunginternet_android": "mirror",
              "webview_android": "mirror",
              "webview_ios": "mirror"
            },
            "status": {
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              "standard_track": true,
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          },
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            "__compat": {
              "description": "`with {type: 'css'}`",
              "tags": [
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              "support": {
                "chrome": {
                  "version_added": "123"
                },
                "chrome_android": "mirror",
                "deno": {
                  "version_added": false
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                "edge": "mirror",
                "firefox": {
                  "version_added": false
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                "firefox_android": "mirror",
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                  "version_added": false
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                "nodejs": {
                  "version_added": false
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                "oculus": "mirror",
                "opera": "mirror",
                "opera_android": "mirror",
                "safari": {
                  "version_added": false
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                "safari_ios": "mirror",
                "samsunginternet_android": "mirror",
                "webview_android": "mirror",
                "webview_ios": "mirror"
              },
              "status": {
                "experimental": true,
                "standard_track": true,
                "deprecated": false
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            }
          },
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            "__compat": {
              "description": "`with {type: 'json'}`",
              "tags": [
                "web-features:json-modules"
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              "support": {
                "chrome": {
                  "version_added": "123"
                },
                "chrome_android": "mirror",
                "deno": {
                  "version_added": "1.37"
                },
                "edge": "mirror",
                "firefox": {
                  "version_added": false,
                  "impl_url": "https://bugzil.la/1736059"
                },
                "firefox_android": "mirror",
                "ie": {
                  "version_added": false
                },
                "nodejs": [
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                    "version_added": "20.10.0"
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                  {
                    "version_added": "18.20.0",
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                ],
                "oculus": "mirror",
                "opera": "mirror",
                "opera_android": "mirror",
                "safari": {
                  "version_added": "17.2"
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                "safari_ios": "mirror",
                "samsunginternet_android": "mirror",
                "webview_android": "mirror",
                "webview_ios": "mirror"
              },
              "status": {
                "experimental": false,
                "standard_track": true,
                "deprecated": false
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            }
          }
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        "service_worker_support": {
          "__compat": {
            "description": "Available in service workers",
            "tags": [
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            "support": {
              "chrome": {
                "version_added": "91"
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              "chrome_android": "mirror",
              "deno": {
                "version_added": false
              },
              "edge": "mirror",
              "firefox": {
                "version_added": false,
                "impl_url": "https://bugzil.la/1360870"
              },
              "firefox_android": "mirror",
              "ie": {
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              "nodejs": {
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              "webview_ios": "mirror"
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              "experimental": false,
              "standard_track": true,
              "deprecated": false
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          }
        },
        "worklet_support": {
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            "description": "Available in worklets",
            "support": {
              "chrome": {
                "version_added": false
              },
              "chrome_android": "mirror",
              "deno": {
                "version_added": false
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              "edge": "mirror",
              "firefox": {
                "version_added": "114"
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                "version_added": false
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                "version_added": false
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              "oculus": "mirror",
              "opera": "mirror",
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                "version_added": false
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            "status": {
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              "standard_track": true,
              "deprecated": false
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          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-labelled-statements",
          "tags": [
            "web-features:snapshot:ecmascript-3",
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            "safari": {
              "version_added": "1"
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            "webview_ios": "mirror"
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          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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        }
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        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/let",
          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-let-and-const-declarations",
          "tags": [
            "web-features:snapshot:ecmascript-2015"
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          "support": {
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              {
                "version_added": "49"
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                "version_added": "41",
                "version_removed": "49",
                "partial_implementation": true,
                "notes": "[Strict mode](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Strict_mode) is required."
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            "deno": {
              "version_added": "1.0"
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            "edge": [
              {
                "version_added": "14"
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              {
                "version_added": "12",
                "version_removed": "14",
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              "version_added": "11",
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            "opera_android": {
              "version_added": "18"
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            "safari": {
              "version_added": "10"
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            "webview_android": "mirror",
            "webview_ios": "mirror"
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          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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        "__compat": {
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              "version_added": "1.0"
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              "version_added": "12"
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              "version_added": "1"
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            "opera_android": {
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            "safari": {
              "version_added": "1"
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            "safari_ios": "mirror",
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            "webview_android": "mirror",
            "webview_ios": "mirror"
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          "status": {
            "experimental": false,
            "standard_track": true,
            "deprecated": false
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        }
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        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/switch",
          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-switch-statement",
          "tags": [
            "web-features:javascript"
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          "support": {
            "chrome": {
              "version_added": "1"
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            "chrome_android": "mirror",
            "deno": {
              "version_added": "1.0"
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            "edge": {
              "version_added": "12"
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            "firefox": {
              "version_added": "1"
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            "firefox_android": "mirror",
            "ie": {
              "version_added": "4"
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            "nodejs": {
              "version_added": "0.10.0"
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            "oculus": "mirror",
            "opera": {
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            "opera_android": {
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            "safari": {
              "version_added": "1"
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            "safari_ios": "mirror",
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            "webview_android": "mirror",
            "webview_ios": "mirror"
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          "status": {
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            "standard_track": true,
            "deprecated": false
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        "__compat": {
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          "spec_url": "https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-throw-statement",
          "tags": [
            "web-features:snapshot:ecmascript-3",
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              "version_added": "1.0"
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          "status": {
            "experimental": false,
            "standard_track": true,
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          "description": "`try...catch`",
          "mdn_url": "https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/try...catch",
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          "tags": [
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          "support": {
            "chrome": {
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            "chrome_android": "mirror",
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              "version_added": "1.0"
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              "version_added": "12"
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              "version_added": "4"
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            "opera_android": {
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            "samsunginternet_android": "mirror",
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          "status": {
            "experimental": false,
            "standard_track": true,
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              "chrome": {
                "version_added": "66"
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              "chrome_android": "mirror",
              "deno": {
                "version_added": "1.0"
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            "status": {
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              "standard_track": true,
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        "__compat": {
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