fast/js/function-argument-evaluation.html

<p>This page tests function calls whose argument expressions overwrite the callee.</p>
<p>If the test passes, you'll see PASS messages below.
</p>
<pre id="console"></pre>

<script>
function log(s)
{
    document.getElementById("console").appendChild(document.createTextNode(s + "\n"));
}

function shouldBe(aDescription, a, b)
{
    if (a === b) {
        log("PASS: " + aDescription + " should be " + b + " and is.");
    } else {
        log("FAIL: " + aDescription + " should be " + b + " but instead is " + a + ".");
    }
}

function test1(callback, x) {
    try {
        return callback.apply(this, [ callback = x ]);
    } catch(e) {
        return e;
    }
};

function test2(callback, x) {
    try {
        return callback(callback = x);
    } catch(e) {
        return e;
    }
};

(function () {
    if (window.testRunner)
        testRunner.dumpAsText();

    var callback = function callback(x) {
        return x;
    };

    shouldBe("test1(callback, 1)", test1(callback, 1), 1);
    shouldBe("test2(callback, 1)", test2(callback, 1), 1);
})();
</script>