juliangruber / array-filter Goto Github PK

The native Array#filter supports a thisArg arg after the fn arg.
See http://es5.github.io/#x15.4.4.20.

The use of hasOwn doesn't follow the spec so creates an inconsistency between when native Array#filter exists and the fallback code. See 119e7f0.

It would be more consistent across environments and more performant if you didn't defer to native Array#filter and instead used a simple for-loop.

Smth like:

module.exports = function (arr, fn, ctx) {
  var ret = [];

  var f = typeof ctx == 'undefined' ? fn : function(val, i, arr) {
    return fn.call(ctx, val, i, arr);
  };

  for (var i = 0, l = arr.length; i < l; i++) {
    var val = arr[i];
    if (f(val, i, arr)) ret.push(val);
  }
  return ret;
};

You'd need to modify the holes tests as now holes will be consistently treated like undefined values.

It seems like thisArg is ignored when support for filter returns true and the uses native array filtering. This is by design?

filter incorrectly allows the fn function to modify the filtered results because it pushes arr[i] instead of getting a reference to it before the fn is called. This is different than the native Array#filter behavior.

See 119e7f0.