MDN, underscore.js, all list code that provide fallback if new native methods aren't found: if (!Array.prototype.map).

The problem with this simple test is that if fails with its intent if Array.prototype.map = "map".

My proposition is an enhanced text: text for feature signature, not just for feature name.

When testing for new native methods, like Array.prototype.map, maybe an extensive test should replace the simple if (!Arrray.prototype.map). Maybe include [native code] string test?

Code:
console.log(Array.prototype.map.toString());

    function map() {
    [native code]
    }
Otherwise:
Code:
Array.prototype.map = "map";
tests true but not for behavior.

I've posted this idea of mine in a few places. I've edited https://developer.mozilla.org/en-US/...ects/Array/map and raised an issue https://github.com/jashkenas/underscore/issues/1312.

I'm curious what the reactions will be. What do SPF finest think?