Javascript Array iterator() method

// Replacing Array.prototype.iterator with a generator affects for-of behavior.

Array.prototype.iterator = function () {
    for (var i = this.length; --i >= 0; )
        yield this[i];//from   ww  w.  ja v a 2 s .  c  o  m
};

var s = '';
for (var v of ['a', 'b', 'c', 'd'])
    s += v;
assertEq(s, 'dcba');