1. 方法返回一个表示改对象的字符串，如果是对象会返回，toString() 返回 “[object type]”,其中type是对象类型
2. valueOf房啊发返回指定对象的原始值，JS会利用 valueOf() 方法用来把对象转换成原始类型的值（数值、字符串和布尔值）

1、JS Boolean

• var boolean = new Boolean();
• console.log(boolean.toString()); //"false"
• console.log(boolean.valueOf()); // false

2、JS Number

• var number = 123;
• console.log(number.toString()); //"123"
• console.log(number.valueOf()); // 123

3、JS String

• var string = '123';
• console.log(string.toString()); //"123"
• console.log(string.valueOf()); // "123"

4、JS Array

• var array = ['aa','bb','cc'];
• console.log(array.toString()); //"aa,bb,cc"
• console.log(array.valueOf()); // ['aa','bb','cc']

5、JS Function

• var function = function() {};
• console.log(function.toString()); //"function() {}"
• console.log(function.valueOf()); // function() {}

6、JS Object

• var object = {};
• console.log(object.toString()); //[object, object]
• console.log(object.valueOf()); // {}

7、JS Date

• var date = new Date();
• console.log(date.toString()); //"Thu Feb 13 2020 11:00:46 GMT+0800 (中国标准时间)"
• console.log(date.valueOf()); // 1581562866267