The implementation of Web NFC in Chromium consists of two main parts: The NFC module in Blink located at third_party/blink/renderer/modules/nfc/ which contains Blink JavaScript bindings for Web NFC and the browser side platform level adaptation that is located at services/device/nfc. The Blink NFC module communicates with the browser adaptation through NFC Mojo interface defined in the services/device/public/mojom/nfc.mojom file and implemented by the services/device/nfc module.
NDEFWriter and NDEFReader are the two primary interfaces of the Web NFC APIs.
The NDEFWriter interface has the write method for writing data to NFC tags. This method will return a promise, which will be resolved when the message is successfully written to a NFC tag or be rejected when errors happened or the process is aborted by setting the AbortSignal in the NDEFWriteOptions.
The NDEFReader interface has the scan method to try to read data from any NFC tag that comes within proximity. Once there is some data found an NDEFReadingEvent carrying the data will be dispatched to the NDEFReader.
The most important classes for Android adaptation are
NfcImpl, NfcTagHandler and NdefMessageUtils.
third_party/blink/web_tests/external/wpt/web-nfc/ and are a mirror of the web-platform-tests GitHub repository.Web NFC API can be only accessed by top-level secure browsing contexts and user permission is required to access NFC functionality. Web NFC API specification addresses security and privacy topics in chapter 7. Security and Privacy.
The device service provides no support for permission checks. When the render process requests access to a NFC this request is proxied through the browser process by NfcPermissionContext which is responsible for checking the permissions granted to the requesting origin.
At the time of writing, only Android platform is supported.
Please refer to the design documentation for more details.