The most accurate way to check JS object's type?

Question

The typeof operator doesn\'t really help us to find the real type of an object.

I\'ve already seen the following code :

Object.prototyp         


        

Answer 1

the Object.prototype.toString is a good way, but its performance is the worst.

http://jsperf.com/check-js-type

Use typeof to solve some basic problem(String, Number, Boolean...) and use Object.prototype.toString to solve something complex(like Array, Date, RegExp).

and this is my solution:

var type = (function(global) {
    var cache = {};
    return function(obj) {
        var key;
        return obj === null ? 'null' // null
            : obj === global ? 'global' // window in browser or global in nodejs
            : (key = typeof obj) !== 'object' ? key // basic: string, boolean, number, undefined, function
            : obj.nodeType ? 'object' // DOM element
            : cache[key = ({}).toString.call(obj)] // cached. date, regexp, error, object, array, math
            || (cache[key] = key.slice(8, -1).toLowerCase()); // get XXXX from [object XXXX], and cache it
    };
}(this));

use as:

type(function(){}); // -> "function"
type([1, 2, 3]); // -> "array"
type(new Date()); // -> "date"
type({}); // -> "object"