JS判断元素为数字的奇异写法分享

这是在阅读underscore(1.3.3)源码中看到的,它的each方法 代码如下: var each = _.each = _.forEach = function(obj, iterator, context) { if (obj == null) return; if (nativeForEach && obj.forEach === nativeForEach) { obj.forEach(iterator, context); } else if (obj.length === +obj.length) { for (var i = 0, l = obj.length; i &l