var foo = 'foo'; var bar = 1; var obj = { id:1, name:'foo' } var array = ['foo','bar'] console.log(Object.prototype.toString.call(foo)); //[object String] console.log(Object.prototype.toString.call(bar)); //[object Number] console.log(Object.prototype.toString.call(obj)); //[object Object] console.log(Object.prototype.toString.call(array)); //[object Array]