第 34 题：简单改造下面的代码，使之分别打印 10 和 20。 #51

jefferyE · 2019-03-15T01:20:35Z

var b = 10;
(function b(){
   b = 20;
   console.log(b); 
})();

我的解法：
1）打印10

var b = 10;
(function b(b) {
 window.b = 20;
 console.log(b)
})(b)

或者

var b = 10;
(function b(b) {
 b.b = 20;
 console.log(b)
})(b)

2）打印20

var b = 10;
(function b(b) {
 b = 20;
 console.log(b)
})(b)

或

var b = 10;
(function b() {
 var b = 20;
 console.log(b)
})()

XiaoLuo01 · 2019-03-15T01:31:11Z

打印 20 :

var b = 10;
(function (){
  b = 20;
  console.log(b);
})();

打印 10:

var b = 10;
(function (){
  console.log(b);
  b = 20;
})();

jjeejj · 2019-03-15T01:44:21Z

打印20
第一种方法：

var b = 10;
(function a(){
   b = 20;
   console.log(b); 
})();

第二种方法：

var b = 10;
(function b(){
   let b = 20;
   console.log(b); 
})();

对于该方法，按照昨天的解答， b 不是无法修改的，但是现在修改成功了

第三种方法：

var b = 10;
(function (){
   b = 20;
   console.log(b); 
})();

打印10

var b = 10;
(function b(b){
   console.log(b); 
   b = 20;
})(b);

IWANABETHATGUY · 2019-03-15T02:23:22Z

干脆一块改造了

var b = 10;
console.log(b);

(function b() {
  var b = 20;
  console.log(b);
})();

ligoudan1 · 2019-03-15T02:23:38Z

打印20和10:

    var b = 10;
    (function b(b){
        b = 20;
        console.log(b); 
    })(b);
 console.log(b);

qewqewzzz · 2019-03-15T02:31:09Z

var b = 10;
(function b(b){
console.log(b);
b = 20;
console.log(b);
})(b);

jackchenl · 2019-03-15T03:02:04Z

var b = 10;
(function b(){
    var b = 20; //or let b = 20;
    console.log(this.b);
    console.log(b); 
})();

LaoLeo · 2019-03-15T03:13:44Z

// 打印20
var b = 10;
(function b(b){
b = 20;
console.log(b);
})(b);

var b = 10;
(function (){
b = 20;
console.log(b);
})();

// 打印10
var b = 10;
(function b(){
b = 20;
console.log(this.b);
})();

ghost · 2019-03-15T05:03:40Z

bran-nie · 2019-03-15T06:20:08Z

var a = 10;
(function a() {
    var a = 20
    console.log(a)
})();
console.log(a);
// 20
// 10

在立即执行函数表达式里，对a进行var声明，是重新声明了一个变量

dorseysen · 2019-03-15T07:31:18Z

    var b = 10;
    (function b(b){
        console.log(window.b);
        b = 20;
        console.log(b); 
    })();

y1324 · 2019-03-15T09:56:22Z

同时打印10 和20

var b = 10;
(function b() {
let b = 20;
console.log(b)
})(b);
console.log(b);

chenchangyuan · 2019-03-16T04:50:11Z

打印10

var b = 10;
(function b(){
   b = 20;
   console.log(window.b);//10 
})();

打印20

var b = 10;
(function b(){
   var b = 20;
   console.log(b);//20
})();

DangoSky · 2019-03-17T05:12:51Z

  var b = 10;
  (function b(){
    console.log(window.b);   // 打印10
    var b = 20;
    console.log(b);     // 打印20
  })();

huanglvming · 2019-03-18T15:55:34Z

var b = 10;
(function b(){
   b = 20;
   console.log(b); 
})();

我的解法：
1）打印10

var b = 10;
(function b(b) {
 window.b = 20;
 console.log(b)
})(b)

或者

var b = 10;
(function b(b) {
 b.b = 20;
 console.log(b)
})(b)

2）打印20

var b = 10;
(function b(b) {
 b = 20;
 console.log(b)
})(b)

或

var b = 10;
(function b() {
 var b = 20;
 console.log(b)
})()

麻烦问一下，打印10的第一种方法和打印20的第一种方法有什么不同，为什么输出的结果不一样？按照我的理解，打印20的第一种方法，函数里的b就是window.b,为什么输出结果不一样？

DangoSky · 2019-03-18T16:56:15Z

@huanglvming

var b = 10;
(function b(){
   b = 20;
   console.log(b); 
})();
我的解法：
1）打印10
var b = 10;
(function b(b) {
 window.b = 20;
 console.log(b)
})(b)
或者
var b = 10;
(function b(b) {
 b.b = 20;
 console.log(b)
})(b)
2）打印20
var b = 10;
(function b(b) {
 b = 20;
 console.log(b)
})(b)
或
var b = 10;
(function b() {
 var b = 20;
 console.log(b)
})()
麻烦问一下，打印10的第一种方法和打印20的第一种方法有什么不同，为什么输出的结果不一样？按照我的理解，打印20的第一种方法，函数里的b就是window.b,为什么输出结果不一样？

打印10的第一种方法：b已经作为参数被传进函数里去了，即使函数内使用 window.b = 20;改变了全局的b也已经对它没有影响了，所以会打印出原先的10。
打印20的第一种方法：函数里的b并不是全局的b，修改它也不会影响到全局的b。
你可能没有注意到一点，基本数据类型的传递只是传递数值，比如此处不管你修改的是函数外的b还是函数内的b都不会对对方造成影响。对象的传递才是按引用传递，一个变了全部都要变，可以了解一下js里关于基本数据类型和引用数据类型内存空间的存储方式。

y1324 · 2019-03-19T02:51:32Z

var b =  10 ; 
( function  b (){ 
   b =  20 ;
    console . log (b); 
})();

我的解法：
1）打印10

var b =  10 ; 
( function  b ( b ) {
  window . b  =  20 ;
  console . log (b) 
})(b)

或者

var b =  10 ; 
( function  b ( b ) {
  b . b  =  20 ;
  console . log (b) 
})(b)

2）打印20

var b =  10 ; 
( function  b ( b ) { 
 b =  20 ;
  console . log (b) 
})(b)

或

var b =  10 ; 
( function  b () {
  var b =  20 ;
  console . log (b) 
})()

麻烦问一下，打印10的第一种方法和打印20的第一种方法有什么不同，为什么输出的结果不一样？按照我的理解，打印20的第一种方法，函数里的b就是window.b,为什么输出结果不一样？

两个作用域不同，所以打印的不一样，第一个是外层的b，window上的。20的第一个打印的函数里面的，b只是在作用于函数里面。

mengfei-nie · 2019-03-21T03:16:40Z

不是很理解这个自执行函数里面的变量被重新赋值后为啥还是输出之前的变量值函数

shizhenbin · 2019-03-26T09:17:37Z

console.log(10);
console.log(20);

jjeejj · 2019-03-26T11:46:56Z

console.log(10);
console.log(20);

你是来搞笑的吗？？？？？？ 😅

hmmoshang · 2019-03-28T04:40:05Z

打印10
var b = 10;
(function b(){
b = 20;
console.log(window.b);
})();
打印20
(function (){
b = 20;
console.log(b);
})();

zhw2590582 · 2019-03-29T06:06:38Z

这题目问得不是很严谨

frjcxy · 2019-03-30T13:55:24Z

console.log(10);
console.log(20);

你是来搞笑的吗？？？？？？ 😅兄台厉害

pangqiang · 2019-04-02T07:57:27Z

var b = 10;
(function b(b){
    console.log(b)
    b = 20;
    console.log(b);
})(b);

yu910709 · 2019-04-03T07:34:39Z

打印10

var b = 10;
(function b(){
   b = 20;
   console.log(window.b);//10 
})();

打印20

var b = 10;
(function b(){
   var b = 20;
   console.log(b);//20
})();

找到一个答案一样的，又没说不能改打印体😂

yu910709 · 2019-04-03T07:36:23Z

不是很理解这个自执行函数里面的变量被重新赋值后为啥还是输出之前的变量值函数

看第33题

qinnnn · 2019-04-09T06:28:09Z

var b = 10;
(function b(){
    var b = 20;
    console.log(this.b);
	console.log(b);
})();

kevinlorry · 2019-07-09T08:21:09Z

我写一下我的理解和解法吧（既然改写应该还是要在原来题目上最小改动）
var b = 10;
(function b(){
var b = 20;
console.log(b);
})();

var b = 10;
(function b(){
b = 20;
console.log(window.b);
})();

chenshiai · 2019-07-10T07:56:40Z

console.log(10,20)
应题目要求，不考虑出题者的意图，第一反应是这个（手动滑稽）

Abiel1024 · 2019-07-10T10:03:16Z

var b = 10;
(function b(){
    b = 20;
    console.log(this.b); 
})();
// 10
var b = 10;
(function b(){
    let b = 20;
    console.log(b); 
})();
// 20

witsaint · 2019-07-11T08:59:50Z

既然能够简单修改代码
打印20
var b = 10; (function(){ b = 20; console.log(b); })();
打印10
var b = 10; (function(){ console.log(b); })();

yipjianbo · 2020-01-13T09:52:25Z

console.log(10);
console.log(20);

特地登陆进来点个赞，这老哥机灵鬼,笑死我了

yipjianbo · 2020-01-13T09:55:15Z

var b = 10;
(function b(){
   b = 20;
   console.log(b); 
})();

输出10

var b = 10;
(function b(){
   b = 20;
   console.log(this.b); 
})();

输出20

var b = 10;
(function b(){
   var b = 20;
   console.log(b); 
})();

zhangqiong27 · 2020-02-21T02:29:49Z

原题：
var b = 10;
(function b(){
b = 20;
console.log(b);
})();
打印20：
(function b(b){
b = 20;
console.log( b);
})(b); // 20

(function b(){
    let b = 20;
    console.log(b);
})();  // 20

打印10：
(function b(){
b = 20;
console.log( this.b);
})(); // 10

Hideer · 2020-02-29T05:37:01Z

QZEming · 2020-03-06T01:13:39Z

原题

var b = 10;
(function b(){
    b = 20;
    console.log(b); 
})();

皮一下
打印10

var b = 10;
(function b(){
    b = 20;
    console.log(10); 
})();

打印20

var b = 10;
(function b(){
    b = 20;
    console.log(20); 
})();

认真做题
打印10

var b = 10;
(function b(){
    b = 20;
    console.log(this.b); 
})();

打印20

var b = 10;
(function b(){
    var b = 20;
    console.log(b); 
})();

devinxiang · 2020-04-02T08:38:16Z

var b = 10;
(function b(b){
    console.log(b)
    var b = 20;
    console.log(b);
})(b);

cMYour · 2020-04-07T04:04:02Z

// 10
var b = 10;
(function b(){
   b = 20;
   // 此时的 this 指向 window 即：全局变量
   console.log(this.b); 
})();

// 20
var b = 10;
(function b(){
   this.b = 20;
   console.log(this.b); 
})();

zhangwen1932 · 2020-05-10T04:46:19Z

  var b = 10;
 (function b() {
      let b=20;
      console.log(window.b);
      console.log(b);
 })();

codexu · 2020-05-27T08:08:03Z

console.log(10)
console.log(20)

jackchang2015 · 2020-06-06T09:36:32Z

//打印10
var b = 10;
(function (){
    console.log(b); 
})();

//
var b = 10;
(function b(){
   b = 20;
    console.log(this.b); 
})();

//打印20

var b = 10;
(function (){
   b = 20;
    console.log(b); 
})();
//
var b = 10;
(function b(){
   let b = 20;
    console.log(b); 
})();

soraly · 2020-06-17T09:50:42Z

var b = 10;
console.log(b);  //10
(function b(){
    var b = 20;
    console.log(b);  //20
})();

zengkaiz · 2020-07-22T09:09:32Z

// 打印20
var  b = 10;
(()=>{
  b = 20
  console.log(b)
})()

// 打印20
var b = 10;
(function b(b){
    b = 20;
    console.log(b); 
})();

// 打印20
var b = 10;
(function b(){
    var b = 20;
    console.log(b); 
})();

// 打印10
var b = 10;
(function b(b){
    window.b = 20;
    console.log(b); 
})(b);

RoeyXie · 2020-08-03T03:37:23Z

// 20

var b = 10;
(function b(){
    var b = 20;
    console.log(b); 
})();

// 10

var b = 10;
(function b(){
    b = 20;
    console.log(window.b); 
})();

LoveFreedom97 · 2020-08-06T10:27:44Z

Emmmm
var b = 10;
(function(){
console.log(b)
b=20;
console.log(b)
})()

zelixag · 2020-08-18T08:47:14Z

这个题目问的不太好，函数表达式的name属于函数作用域的且不能重新复制，类似const定义，可以用来调用。

lsczy · 2020-08-25T00:55:01Z

var b = 10; 
(function b(b) {
   b = 20;
   console.log(window.b) // 10
   console.log(b)        // 20
})(b)

HeartYangj · 2020-09-10T08:59:17Z

var b = 10;
(function b(b) {
console.log(b);
b = 20;
console.log(b);
})(b);

m7yue · 2020-09-11T03:50:38Z

// 10
var b = 10;
(function b(){
    b = 20;
    console.log(window.b); 
})();

// 20
var b = 10;
(function b(){
    let b = 20;
    console.log(b); 
})();

BlackCloverM · 2020-09-14T05:51:20Z

console.log(10);
console.log(20);

你是来搞笑的吗？？？？？？ 😅

真把我逗笑了

BarneyRoos · 2021-01-04T07:50:42Z

//不太明白这题在考啥
var b = 10;
(function b(num){
    console.log(num)
    num = 20;
    console.log(num);
})(b);

wangsiyuan4 · 2022-02-11T02:38:17Z

var b = 10;
(function b() {
console.log(window.b)
let b = 20;
console.log(b);
})();

Yangfan2016 · 2022-08-04T12:11:50Z

// 打印 10
var b = 10;
(function b(c) {
 b = 20;
 console.log(c)
})(b)

// 打印20
var b = 10;
(function b(b) {
 b = 20;
 console.log(b)
})(b)

weijuer · 2022-11-17T08:19:08Z

// 10
var b = 10;
(function (){
    console.log(b); 
    b = 20;
})();

// 20
var b = 10;
(function (){
    b = 20;
    console.log(b); 
})();

18920199681 · 2022-11-22T08:50:24Z

var b = 10;
(function b(b){
    b = 20;
    console.log(this.b); 
    console.log(b); 
})(b);

liyi711 · 2022-12-22T09:33:45Z

打印20：

var b = 10;
(function b(){
  var  b = 20;
   console.log(b);
})()

打印10：

var b = 10;
(function b(){
  b = 20;
   console.log(this.b);
})()

XW666 · 2023-04-28T02:12:47Z

 var b = 10;
  (function b() {
    var b = 20;
    console.log(b);
    console.log(this.b)
  })();

XW666 · 2023-04-28T02:14:20Z

 var b = 10;
  (function b() {
    var b = 20;
    console.log(b);
    console.log(this.b)
  })();

Chenmin926 · 2023-06-19T01:37:08Z

// 打印 10
var b = 10;
(function b(){
b = 20;
console.log(window.b);
})();

// 打印20
var b = 10;
(function b(){
window.b = 20;
console.log(window.b);
})();

npmrun · 2023-08-02T09:15:59Z

console.log(10);
console.log(20)

lovelmh13 mentioned this issue Jan 30, 2020

简单改造下面的代码，使之分别打印 10 和 20 lovelmh13/One-question-a-day#11

Open

第 34 题：简单改造下面的代码，使之分别打印 10 和 20。 #51

第 34 题：简单改造下面的代码，使之分别打印 10 和 20。 #51

Comments

jefferyE commented Mar 15, 2019 • edited Loading

XiaoLuo01 commented Mar 15, 2019

jjeejj commented Mar 15, 2019

IWANABETHATGUY commented Mar 15, 2019

ligoudan1 commented Mar 15, 2019

qewqewzzz commented Mar 15, 2019

jackchenl commented Mar 15, 2019 • edited by yygmind Loading

LaoLeo commented Mar 15, 2019

ghost commented Mar 15, 2019

bran-nie commented Mar 15, 2019 • edited Loading

dorseysen commented Mar 15, 2019

y1324 commented Mar 15, 2019

chenchangyuan commented Mar 16, 2019

DangoSky commented Mar 17, 2019

huanglvming commented Mar 18, 2019

DangoSky commented Mar 18, 2019

y1324 commented Mar 19, 2019

mengfei-nie commented Mar 21, 2019

shizhenbin commented Mar 26, 2019

jjeejj commented Mar 26, 2019

hmmoshang commented Mar 28, 2019

zhw2590582 commented Mar 29, 2019

frjcxy commented Mar 30, 2019

pangqiang commented Apr 2, 2019

yu910709 commented Apr 3, 2019

yu910709 commented Apr 3, 2019

qinnnn commented Apr 9, 2019 • edited by yygmind Loading

kevinlorry commented Jul 9, 2019

chenshiai commented Jul 10, 2019

Abiel1024 commented Jul 10, 2019

witsaint commented Jul 11, 2019

yipjianbo commented Jan 13, 2020

yipjianbo commented Jan 13, 2020

zhangqiong27 commented Feb 21, 2020

Hideer commented Feb 29, 2020

QZEming commented Mar 6, 2020

devinxiang commented Apr 2, 2020

cMYour commented Apr 7, 2020

zhangwen1932 commented May 10, 2020

codexu commented May 27, 2020

jackchang2015 commented Jun 6, 2020 • edited Loading

soraly commented Jun 17, 2020

zengkaiz commented Jul 22, 2020

RoeyXie commented Aug 3, 2020

LoveFreedom97 commented Aug 6, 2020

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lsczy commented Aug 25, 2020 • edited Loading

HeartYangj commented Sep 10, 2020

m7yue commented Sep 11, 2020

BlackCloverM commented Sep 14, 2020

BarneyRoos commented Jan 4, 2021

wangsiyuan4 commented Feb 11, 2022

Yangfan2016 commented Aug 4, 2022

weijuer commented Nov 17, 2022

18920199681 commented Nov 22, 2022

liyi711 commented Dec 22, 2022

XW666 commented Apr 28, 2023

XW666 commented Apr 28, 2023

Chenmin926 commented Jun 19, 2023

npmrun commented Aug 2, 2023

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edited

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edited by yygmind

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