function makeAdder(a) { return function(b) { return a + b; } } x = makeAdder(5); y = makeAdder(20); x(6);//11 y(7);//27
var a = ["dog", "cat", "hen"]; a[100] = "fox"; a.length == 101 //true //for循环的简单写法 for (var i = 0, item; item = a[i++];) { console.log(item); } //这种写法不能遍历数组中含有 "" 、false、0等等
