28 个 JavaScript 编程黑科技:还有这种操作!

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2020-11-14 19:49

Javascript 是一门很厉害的语言,我可能学了假的 JavaScript,哈哈,大家还有什么推荐的,欢迎补充。

1、单行写一个评级组件

"★★★★★☆☆☆☆☆".slice(5 - rate, 10 - rate);

定义一个变量rate是1到5的值,然后执行上面代码,看图

才发现插件什么的都弱爆了

2、如何装逼用代码骂别人SB

  1. (!(~+[])+{})[--[~+""][+[]]*[~+[]] + ~~!+[]]+({}+[])[[~!+[]]*~+[]]

3、如何用代码优雅的证明自己NB

这个牛逼了

  1.    console.log(([][[]]+[])[+!![]]+([]+{})[!+[]+!![]])

4、JavaScript 错误处理的方式的正确姿势

???,舅服你

  1. try {

  2.    something

  3. } catch (e) {

  4.    window.location.href =

  5.        "http://stackoverflow.com/search?q=[js]+" +

  6.        e.message;

  7. }

5、从一行代码里面学点JavaScript

  1. [].forEach.call($$("*"),function(a){

  2.    a.style.outline="1px solid #"+(~~(Math.random()*(1<<24))).toString(16)

  3. })

翻译成正常语言就是这样的

  1. Array.prototype.forEach.call(document.querySelectorAll('*'),

  2. dom => dom.style.outline = `1px solid #${parseInt(Math.random() *

  3. Math.pow(2,24)).toString(16)}`)

接下来在浏览器控制看看:something magic happens

6、论如何优雅的取随机字符串

  1. Math.random().toString(16).substring(2) // 13位

  2. Math.random().toString(36).substring(2) // 11位

7、(10)"toString" === "10"

8、匿名函数自执行

这么多写法你选择哪一种?我选择死亡。

  1. ( function() {}() );

  2. ( function() {} )();

  3. [ function() {}() ];



  4. ~ function() {}();

  5. ! function() {}();

  6. + function() {}();

  7. - function() {}();



  8. delete function() {}();

  9. typeof function() {}();

  10. void function() {}();

  11. new function() {}();

  12. new function() {};



  13. var f = function() {}();



  14. 1, function() {}();

  15. 1 ^ function() {}();

  16. 1 > function() {}();

  17. // ...

9、另外一种undefined

从来不需要声明一个变量的值是undefined,因为JavaScript会自动把一个未赋值的变量置为undefined。所有如果你在代码里这么写,会被鄙视的

  1. var data = undefined;

但是如果你就是强迫症发作,一定要再声明一个暂时没有值的变量的时候赋上一个undefined。那你可以考虑这么做:

  1. var data = void 0; // undefined

void在JavaScript中是一个操作符,对传入的操作不执行并且返回undefined。void后面可以跟()来用,例如void(0),看起来是不是很熟悉?没错,在HTML里阻止带href的默认点击操作时,都喜欢把href写成javascript:void(0),实际上也是依靠void操作不执行的意思。

当然,除了出于装逼的原因外,实际用途上不太赞成使用void,因为void的出现是为了兼容早起ECMAScript标准中没有undefined属性。void 0的写法让代码晦涩难懂。

10、论如何优雅的取整

  1. var a = ~~2.33



  2. var b= 2.33 | 0



  3. var c= 2.33 >> 0

11、如何优雅的实现金钱格式化:1234567890 --> 1,234,567,890

用正则魔法实现:

  1. var test1 = '1234567890'

  2. var format = test1.replace(/\B(?=(\d{3})+(?!\d))/g, ',')



  3. console.log(format) // 1,234,567,890

非正则的优雅实现:

  1. function formatCash(str) {

  2.       return str.split('').reverse().reduce((prev, next, index) => {

  3.            return ((index % 3) ? next : (next + ',')) + prev

  4.       })

  5. }

  6. console.log(formatCash('1234567890')) // 1,234,567,890

12、这个我服,还有这个你很机智

我服

  1. while (1) {

  2.    alert('牛逼你把我关了啊')

  3. }

你很机智,好一个障眼法

  1. 清除缓存: href="javascript:alert('清除成功');">清除缓存

13、逗号运算符

  1. var a = 0;

  2. var b = ( a++, 99 );

  3. console.log(a);  // 1

  4. console.log(b);  // 99

14、论如何最佳的让两个整数交换数值

常规办法:

  1. var a=1,b=2;

  2. a += b;

  3. b = a - b;

  4. a -= b;

缺点也很明显,整型数据溢出,对于32位字符最大表示数字是2147483647,如果是2147483645和2147483646交换就失败了。黑科技办法:

  1. a ^= b;

  2. b ^= a;

  3. a ^= b;

哈哈?,看不懂的童鞋建议去补习一下C语言的位操作,我就不去复习了,以前学嵌入式时候学的位操作都忘了

15、实现标准JSON的深拷贝

  1. var a = {

  2.    a: 1,

  3.    b: { c: 1, d: 2 }

  4. }

  5. var b=JSON.parse(JSON.stringify(a))

不考虑IE的情况下,标准JSON格式的对象蛮实用,不过对于undefined和function的会忽略掉。

16、不用Number、parseInt和parseFloat和方法把"1"字符串转换成数字

哈哈,不准用强制类型转换,那么就想到了强大了隐式转换

  1. var a =1

  2. +a

17、如何装逼的写出"hello world!"

滚动条很长哦?

  1. ([]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+(!![]+[])[+[]]+([][[]]+[])[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]])())[+[]]+([][[]]+[])[!+[]+!![]+!![]]+(![]+[])[!+[]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+([][[]]+[])[+[]]+([][[]]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(![]+[])[!+[]+!![]+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+([]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+(!![]+[])[+[]]+([][[]]+[])[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]])())[!+[]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]])()([][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(![]+[])[!+[]+!![]+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+([]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+(!![]+[])[+[]]+([][[]]+[])[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]])())[!+[]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]])()(([]+{})[+[]])[+[]]+(!+[]+!![]+!![]+!![]+!![]+!![]+!![]+[])+(!+[]+!![]+!![]+!![]+!![]+!![]+!![]+[]))+([]+{})[+!![]]+(!![]+[])[+!![]]+(![]+[])[!+[]+!![]]+([][[]]+[])[!+[]+!![]]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+([][[]]+[])[+[]]+([][[]]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(![]+[])[!+[]+!![]+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+([]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+(!![]+[])[+[]]+([][[]]+[])[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]])())[!+[]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]])()([][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(![]+[])[!+[]+!![]+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+([]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+(!![]+[])[+[]]+([][[]]+[])[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]])())[!+[]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]])()(([]+{})[+[]])[+[]]+(!+[]+!![]+[])+(+!![]+[]))

居然能运行,牛逼的隐式转换

18、parseInt(0.0000008) === 8

19、++[[]][+[]]+[+[]] == 10

强大的隐式转换,23333

20、0.1 + 0.2 == 0.3

0.1+0.2==0.3 竟然是不成立的。。。。所以这就是为什么数据库存储对于货币的最小单位都是分。

简单说, 0.10.2的二进制浮点表示都不是精确的,所以相加后不是 0.3,接近(不等于)0.30000000000000004

所以,比较数字时,应该有个宽容值。ES6中这个宽容值被预定义了:Number.EPSILON

21、最短的代码实现数组去重

  1. [...new Set([1, "1", 2, 1, 1, 3])]

前不久面试阿里就问了这道题,哈哈,所以也写上一下

22、用最短的代码实现一个长度为m(6)且值都n(8)的数组

  1. Array(6).fill(8)

这个够短了吧,好像是当初哪里看到的一个面试题,就自己想到了ES6的一些API

23、短路表达式

条件判断

  1. var a = b && 1

  2.    // 相当于

  3. if (b) {

  4.    a = 1

  5. } else {

  6.    a = b

  7. }



  8. var a = b || 1

  9.    // 相当于

  10. if (b) {

  11.    a = b

  12. } else {

  13.    a = 1

  14. }

24、JavaScript版迷宫

逃出迷宫,2333

25、取出一个数组中的最大值和最小值

  1. var numbers = [5, 458 , 120 , -215 , 228 , 400 , 122205, -85411];

  2. var maxInNumbers = Math.max.apply(Math, numbers);

  3. var minInNumbers = Math.min.apply(Math, numbers);

26、将argruments对象转换成数组

  1. var argArray = Array.prototype.slice.call(arguments);



  2. 或者ES6



  3. var argArray = Array.from(arguments)

27、javascript高逼格之Function构造函数

很多JavaScript教程都告诉我们,不要直接用内置对象的构造函数来创建基本变量,例如var arr = new Array(2); 的写法就应该用var arr = [1, 2];的写法来取代。

但是,Function构造函数(注意是大写的Function)有点特别。Function构造函数接受的参数中,第一个是要传入的参数名,第二个是函数内的代码(用字符串来表示)。

  1. var f = new Function('a', 'alert(a)');

  2. f('jawil'); // 将会弹出窗口显示jawil

这种方式可以根据传入字符串内容来创建一个函数 是不是高大上?!

28、从一个数组中找到一个数,O(n)的算法,找不到就返回 null。

正常的版本:

  1. function find (x, y) {

  2.  for ( let i = 0; i < x.length; i++ ) {

  3.    if ( x[i] == y ) return i;

  4.  }

  5.  return null;

  6. }



  7. let arr = [0,1,2,3,4,5]

  8. console.log(find(arr, 2))

  9. console.log(find(arr, 8))

结果到了函数式成了下面这个样子(好像上面的那些代码在下面若影若现,不过又有点不太一样,为了消掉if语言,让其看上去更像一个表达式,动用了 ? 号表达式):

  1. //函数式的版本

  2. const find = ( f => f(f) ) ( f =>

  3.  (next => (x, y, i = 0) =>

  4.    ( i >= x.length) ?  null :

  5.      ( x[i] == y ) ? i :

  6.        next(x, y, i+1))((...args) =>

  7.          (f(f))(...args)))



  8. let arr = [0,1,2,3,4,5]

  9. console.log(find(arr, 2))

  10. console.log(find(arr, 8))

最后奉劝大家一句:莫装逼、白了少年头,2333。。。

源自:https://segmentfault.com/a/1190000010752361

声明:文章著作权归作者所有,如有侵权,请联系小编删除。


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