javascript检测对象的类型
/*
'typeof' and 'instanceof' isn't a reliable method to find
out the object class, so this is a function that does this in a more trustable way.
*/
function is(type, obj) {
var clazz = Object.prototype.toString.call(obj).slice(8, -1);
return obj !== undefined && obj !== null && clazz === type;
}
is('String', 'test'); // true
is('String', new String('test')); // true
