【备忘】javascript原型、Function、eval、闭包、json处理、类、arguments不定

   function foo() {
    }

    // foo.prototype.sayHello = function (a) {
    //     console.log(a)
    // }
    foo.prototype = {
        func: function () {
            console.log("func")
        },
        sayHello: function (a) {
            console.log(a)
        }
    };

    var p = new foo();
    p.sayHello("sayHello");
    p.func();


    var o = {
        go: function () {
            console.log("sayHello")
        }
    };
    var o1 = Object.create(o);
    o1.go();

    var list = Object.create([]);
    list.push("A");
    list.push("B", "C", "D", "E", "F", "G")
    for (let i = 0; i < list.length; i++) {
        console.log("" + i + "" + ": " + list[i])
    }

 

    function foo() {
        console.log("foo")
    }

    // 等价于
    var func = Function("console.log(\"foo\")");
    func()

    var func = Function(foo());
    func()

    function cmp(a, b, c) {
        return Math.max(a, b, c)
    }

    var max = new Function('a', 'b', 'c', 'return cmp(a, b, c)')
    console.log(max(11, 22, 33));

 

    var a = eval("var num = 10;")
    console.log(num);

    var o = eval("({name:'kaka',age:19})")
    console.log(o.name)

 

    function foo() {
        var num = Math.random();

        function func() {
            return num;
        }

        return func;

    }

    var f = foo();
    var res1 = f();
    var res2 = f();

    console.log(res1);
    console.log(res2);



    function goo() {
        var o = {name: "kaka"};
        return function () {
            return o;
        }
    }

    var g = goo();
    var ret = g();
    console.log(ret.name);
    // 函数科里化（高阶函数）
    console.log(goo()());

    

    function hoo() {
        var num = Math.random();
        return {
            get_num: function () {
                return num;
            },
            set_num: function (value) {
                num = value;
            }
        }
    }

    var t = hoo();
    var num = t.get_num();
    console.log(num);

    t.set_num(1);
    num = t.get_num();
    console.log(num);

 

    var str1 = '{ "name": "kaka", "sex": "man" }';

    var obj = JSON.parse(str1); //由JSON字符串转换为JSON对象
    console.log(obj);
    console.log(typeof (obj));

    var obj2 = eval('(' + str1 + ')'); //由JSON字符串转换为JSON对象
    console.log(obj2);
    console.log(typeof (obj2));

    var last = JSON.stringify(obj); //将JSON对象转化为JSON字符
    console.log(last);
    console.log(typeof (last));

 

class Demo {
    constructor(a, b) {
        this.a = a;
        this.b = b;
        return this;
    }

    print() {
        console.log(this.a + ' ' + this.b);
    }
}；
const demo = new Demo('hello', 'world').print();
console.log(typeof demo);

class Point {
    string(){
        return 'aaa'
    }
}
class ColorPoint extends Point {
    constructor(color) {
        super(); // 调用父类的constructor()
        this.color = color;
    }

    toString() {
        return (this.string() )
    }
}
console.log(new ColorPoint('#000'));    //console.log(new ColorPoint(1,2,'#000'))
console.log(new ColorPoint('#000').toString());     //aaa

console.log(new ColorPoint('#000').__proto__);      //Point {constructor: function, toString: function}
console.log(ColorPoint.__proto__);      // class Point{...}
console.log(ColorPoint.prototype);      // Point {constructor: function, toString: function}
console.log(ColorPoint.__proto__.prototype);      // Object {constructor: function, string: function}

 

function printThe() {
    for (let i = 0; i < arguments.length; i++) {
      return arguments
    }
  }

  console.log(printThe(1, 2, 3, 4, 5, 6));

  const arr = [1, 2, 3, 4, 5, 6];

  function printTheTwo() {
    arr.forEach((item, index) => {
      console.log(item)
    })
  }

  printTheTwo();

  const obj = [{id: 1, name: "a"},
    {id: 2, name: "b"},
    {id: 3, name: "c"},
    {id: 4, name: "d"}];

  function printTheThree() {
    obj.forEach((item, index) => {
      console.log(item)
    })
  }

  printTheThree()