$typeof.js

/**
 * 判断对象的类型
 * @param  {Object} obj 
 * @return {String} 
 */
function $typeof(obj) { 
    return Object.prototype.toString.call(obj).replace(/^\[object |\]$/g,'').toLowerCase();
}
 
 
/* Usage:
 
$typeof({})             #=> 'object'
$typeof([])             #=> 'array'
$typeof('')             #=> 'string'
$typeof(1)              #=> 'number'
$typeof(true)           #=> 'boolean'
$typeof(null)           #=> 'null'
$typeof(undefined)      #=> 'undefined'
$typeof(function() {})  #=> 'function'
$typeof(new Map())      #=> 'map'
$typeof(new WeakMap())  #=> 'weakmap'
$typeof(new Set())      #=> 'set'
$typeof(new WeakSet())  #=> 'weakset'
$typeof(Symbol('1'))    #=> 'symbol'
*/

Very useful thanks