javascript类型检测

主要有typeof和instanceof。其中typeof可以检测出string, number, function, boolean, undefined，其他的都认为是object.

要确定具体的object类型需要用instanceof

var obj1 = {};  //typeof obj1 => 'object'var obj2 = [1, 2, 3]; // typeof obj2 => 'object'//obj1 instanceof Array => false//obj2 instanceof Array => true