es5_JSON

let str = '[{"name":"大胖","age":23},{"name":"骚胖","age":24}]';
        let arr = [
            {"name":"大胖","age":23},
            {"name":"骚胖","age":24}
            ];

• 用来将json字符串转成json对象(json的反序列化)：

let jsonObj = JSON.parse(str);
       console.log(jsonObj);//打印出[Object, Object] 

• 用来将json对象转成json字符串(json的序列化)：

let jsonStr = JSON.stringify(arr);
    console.log(jsonStr);//打印出[{"name":"大胖","age":23},{"name":"骚胖","age":24}]

• String trim：

 let str5 = '       abc';
    console.log("|"+str5+"|");//打印出|       abc|
    console.log("|"+str5.trim()+"|");//打印出|abc|

• 正则：

 let reg = /^(\s+)|(\s+)$/g;
    console.log("|"+str5.replace(reg,'')+"|");//打印出|abc|

• Date：

console.log(Date.now());//打印出1500706861909
console.log(new Date().toJSON());//打印出2017-07-22T07:01:01.909Z
console.log(new Date().toISOString().slice(0,10));//打印出2017-07-22

• Number：

let a = new Number(1.326);
    let b = new Number(1.324);
    console.log(a.toFixed(2));//打印出1.33
    console.log(b.toFixed(2));//打印出1.32
    let c = 10000000000000;
    console.log(c.toPrecision(4));//打印出1.000e+13
    console.log(Math.round(12.34));//打印出12

• function call apply：

var x = 1;
    let obj5 = {
        x:2
    }
    function fn1(a,b){
        console.log(this.x);
    }
    fn1();
    let fn2 = fn1.bind(obj5);
    fn2();