闭包练习题

变量提升/作用域链练习题

    var a = [1];
    var b =a;
    b=[2];
    console.log(a);

----------------------------

    var a =[1];
    b = a;
    b[1]='a';
    console.log(a);

----------------------------

 //1.
    console.log(a);
    var a = 13;
    function fn() {
        console.log(a);
        var a = 1;
    }
    fn();
    console.log(a);

--------------------

    //2.
    console.log(a);
    var a = 13;
    function fn1() {
        console.log(a);
        a = 1;
    }
    console.log(a);

--------------------

    //3.
    //console.log(a);
    a = 13
    function fn() {
        console.log(a);
        a = 1;
    }
    fn();
    console.log(a);

---------------------

    //4.
    var foo = 1;
    function bar() {
        if (!foo) {
            var foo = 10
        }
        console.log(foo);
    }
    bar();

----------------------

    //5.
    function f5() {
        f=ff();
        return f;
        function ff() {
            return "f" in window;
        };
        var f;
    }
    console.log(f5());
    
--------------------------

    //6.
    var a = b = c = [1, 2, 3, 4];
    b = 9;
    a[1] = 0;
    console.log(b[0]);
    a = [1, 2, 3, 4];
    c = [1, 2, 3, 4];
    a[0] = b;
    console.log(c);
    console.log(a);
    
--------------------------

    //7.
    var ary = [1, 2, 3, 4];
    function ff(ary) {
        ary[0] = 0;
        ary = [0];
        ary[0] = 100;
        return ary
    }
    var s = ff(ary);
    console.log(ary);
    console.log(s);

-------------------------------

 //  8.
    var a = 10, b = 11, c = 12;
    function test(a) {
        a = 1;
        var b = 2;
        c = 3;
    }
    test(10);
    console.log(a);
    console.log(b);
    console.log(c);

--------------------------------

// 9
    var fs = "hello";
    (function (fs) {
        console.log(fs);
        var fs = fs || "world";
        console.log(fs);
    })(fs);
    console.log(fs);

----------------------------------

    var a = 9;
    function ss() {
        a = 0;
        return function (b) {
            return b + (a++)
        }
    }
    var f = ss();
    var m = f(5);
    console.log(m);
    var n = ss()(5);
    console.log(n);
    var x = f(5);
    console.log(x);
    console.log(a);

-------------------------------

//10 
console.log(getA); 
if("a" in window){ 
    var a="1";
    function getA(a) { 
        a=a||this.a;
        console.log(a);
    }
    getA(a);
}

-----------------------------

//11----------(易错!!!!)
var a=2;
var obj1={
    a:1,
    fn1:(function (a) {
        this.a=a;
        a++;
        return function () {
            this.a=a++;
            console.log(a);
        }
    })(a)
};
obj1.fn1();
var fn1=obj1.fn1;
fn1();

-------------------------------------

//12---------------(易错)
f = function () {return true;};
g = function () {return false;};
(function () {
  if (g() && [] == ![]) {
    f = function () {
      return false;
    };
    return  console.log(f())
  }
  function g() {
      return true;
    };
})();
console.log(f());
console.log(g());

------------------------------------

var num =2;
    var obj = {
        num : 0,
        fn : function () {
            num = 1;
            // this-->obj
            (function (num) {
                // this --> window
                ++this.num;
                num++;
                console.log(num)
            })(this.num)
        }
    }
    obj.fn();
    console.log(window.num,obj.num)

---------------------------------------------

var num =1;
    var obj = {
        num : 2,
        fn : (function () {
            this.num *= 2;
            num +=3;
            var num =1;
            return function () {
                num +=2;
                this.num +=2
                console.log(++num)
            }
        })()
    };
    var f= obj.fn;
    f();
    obj.fn();
    console.log(window.num,obj.num)

-----------------------------------------------

 1. var num = 2
    var obj = {num: 1};
    obj.fn = (function (num) {
        this.num += 2;
        num--;
        return function (n) {
            this.num += 2;
            num--;
            console.log(n + ++num);
        }
    })(this.num);
    var fn = obj.fn;
    fn(2);
    obj.fn(1);
    console.log(num, obj.num);

------------------------------------

 2. var num = 10;
    var obj = {num: 15};
    obj.fn = (function (num) {
        this.num += 10;
        num *= 2;
        return function (n) {
            this.num += n;
            console.log(n + (--num));
        }
    })(obj.num);
    var fn = obj.fn;
    fn(10);
    obj.fn(15);
    console.log(window.num, obj.num);

-----------------------------------------

 3. var number =2;
    var obj = {
        number :4, 
        fn1 : (function () {
            this.number*=2;
            number = number*2; 
            var number = 3; 
            return function () {
                this.number*=2;
                number*=3;
                console.log(number); 
            }
        })()
    };
    var fn1 = obj.fn1;
    fn1(); obj.fn1();
    console.log(window.number,obj.number);

---------------------------------------

1.
console.log(getA);

if("a" in window){
    var a="";
    function getA(a) {
        a=a||this.a;
        console.log(this.a);
    }
    getA(a);
}

---------------------------------------

//2.
var a=2;
var obj1={
    a:1,
    fn1:(function (a) {
        this.a=a;
        a++;
        return function () {
            this.a=a++;
            console.log(a);
        }
    })(a)
};
obj1.fn1();
var fn1=obj1.fn1;
fn1();

--------------------------------------------

//3.

var ary=[1,2,3,4];
ary.forEach(function(item,index){
    ary[index]=this;
});
console.log(ary);

----------------------------------------------

//4.
var b="b";
var obj2={
    b:"B",
    getB:function (b) {
        this.b=b+this.b;
        return this.b
    }
};
console.log(obj2.getB("是"));

----------------------------------------------

//5.
var aa=20;
function bind() {
    var aa=12;
    function fn() {
        console.log(this.aa);
    }
    box.onclick=function () {
        fn();
    }
}
box.onclick();

//6.
var c=3;
function getC() {
    this.c++;
    return function (c) {
        c=this.c*2;
        console.log(c);
    }
}
var obj3={
    c:2,
    getC:(function () {//this.getC
        this.c-=1;
        return this.getC
    })()
};
getC(); 
obj3.getC();
var f3=obj3.getC;
f3();
console.log(window.c);
console.log(obj3.c);

---------------------------------------------

//7.
function g1() {
    this.g="gg"
}
var obj4={
    g1:g1,
    gg:function () {
        g1();
    }
};
obj4.g1();
obj4.gg();
console.log(obj4);
console.log("g" in window);

------------------------------------------

//9
  var number=2;
  var obj={
    number:4,
    fn1:(function () {
      this.number*=2;
      number=number*2;
      var number=3;
      return function () {
        this.number*=2;
        number*=3;
        alert(number);
      }
    })()
  };
  var fn1=obj.fn1;
  alert(number);
  fn1();
  obj.fn1();
  alert(window.number);
  alert(obj.number);

--------------------------------------------

    function fn(b) {
        console.log(b);
        if(1!=2){
            console.log(b);
            function b() {
                console.log(b);
            }
            b();
            console.log(b);
        }
        console.log(b);
        b()
    }
    fn(1);

------------------------------------

    if(false){
        var a =1
    }
    console.log(a);


----------------------------------

**原型练习题

原型作业题

// 
function C1(name){
    if(name) this.name = name;
}
function C2(name){
    this.name =name;
}
function C3(name){
    this.name = name ||'join';
}
C1.prototype.name='Tom';
C2.prototype.name='Tom';
C3.prototype.name='Tom';
  console.log(new C1().name);
  console.log(new C2().name);
  console.log(new C3().name)
  
-----------------------------------------

function fun(){
    this.a=0;
    this.b=function(){
        alert(this.a);
    }
}
fun.prototype={
    b:function(){
        this.a=20;
        alert(this.a);
    },
    c:function(){
        this.a=30;
        alert(this.a)
    }
}
var my_fun=new fun();
my_fun.b();
my_fun.c();

----------------------------------------------

function Foo() {
    getName = function () {
        console.log(1);
    };
    return this;
}
Foo.getName = function () {
    console.log(2);
};
Foo.prototype.getName = function () {
    console.log(3);
};
var getName = function () {
    console.log(4);
};
function getName() {
    console.log(5);
}

Foo.getName();
getName();
Foo().getName();
getName();
new Foo.getName();
new Foo().getName();

--------------------------------------------

function Fn() {
    this.x = 100;
    this.y = 200;
    this.getX = function () {
        console.log(this.x);
    }
}
Fn.prototype.getX = function () {
    console.log(this.x);
};
Fn.prototype.getY = function () {
    console.log(this.y);
};
var f1 = new Fn;
var f2 = new Fn;
console.log(f1.getX === f2.getX);
console.log(f1.getY === f2.getY);
console.log(f1.__proto__.getY === Fn.prototype.getY);
console.log(f1.__proto__.getX === f2.getX);
console.log(f1.getX === Fn.prototype.getX);
console.log(f1.constructor);
console.log(Fn.prototype.__proto__.constructor);
f1.getX();
f1.__proto__.getX();
f2.getY();
Fn.prototype.getY();

-----------------------------------------------

var name = 'zhufengpeixun'
var Fn =function (name){
    var name = 'world'
    this.name = 'zhufeng'
    this.sex =function(){
        this.name = 'hello'
    }
}
var f1 = new Fn(name)
var f2 = new Fn('age')
console.log(f1.name)
console.log(f2.age)
f1.sex()
console.log(f1)
f1.sex === f2.sex
Fn.name == f1.name

--------------------------------------

function Fn(){
    var a =1
    this.a = a
}
Fn.prototype.say = function(){
    this.a = 2
}
Fn.prototype = new Fn
f1.__proto__.b = function (){
    this.a = 3
}
var f1 = new Fn
console.log(f1.a)
console.log(f1.prototype)
console.log(f1.b)
f1.hasOwnProperty('b')
'b' in f1
f1.constructor == Fn

--------------------------------------

    var num = 0;
    function Fn(num) {
        arguments[0] = 10;
        this.num = 20;
        return num;
    }
    Fn.num = 40;
    Fn.prototype.num = 30;
    var f = new Fn(num);
    Fn.prototype.getNum = function () {
        console.log(this.num);
    };
    console.log(f.num);
    f.getNum();
    Fn.prototype.getNum();
    console.log(num)
    var n = Fn(num);
    console.log(n);
    console.log(num);

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