【轉】這些JavaScript編程黑科技，裝逼指南，高逼格代碼，讓你驚嘆不已

Javascript是一門很吊的語言，我可能學了假的JavaScript，哈哈，大家還有什么推薦的

本文秉承着：你看不懂是你SB，我寫的代碼就要牛逼。

1、單行寫一個評級組件

"★★★★★☆☆☆☆☆".slice(5 - rate, 10 - rate);定義一個變量rate是1到5的值，然后執行上面代碼，看圖

才發現插件什么的都弱爆了

2、如何裝逼用代碼罵別人SB

(!(~+[])+{})[--[~+""][+[]][~+[]] + !+[]]+({}+[])[[~!+[]]~+[]]

3、如何用代碼優雅的證明自己NB

這個牛逼了

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

4、JavaScript 錯誤處理的方式的正確姿勢

😂😂😂，舅服你

try { something } catch (e) { window.location.href = "http://stackoverflow.com/search?q=[js]+" + e.message; } 

5、從一行代碼里面學點JavaScript

[].forEach.call($$("*"),function(a){ a.style.outline="1px solid #"+(~~(Math.random()*(1<<24))).toString(16) }) 

翻譯成正常語言就是這樣的

Array.prototype.forEach.call(document.querySelectorAll('*'), dom => dom.style.outline = `1px solid #${parseInt(Math.random() * Math.pow(2,24)).toString(16)}`) 

接下來在瀏覽器控制看看：something magic happens

具體分析請參見這篇文章：從一行代碼里面學點JavaScript

6、論如何優雅的取隨機字符串

Math.random().toString(16).substring(2) // 13位 Math.random().toString(36).substring(2) // 11位 

7、(10)"toString" === "10"

8、匿名函數自執行

這么多寫法你選擇哪一種？我選擇死亡。

( function() {}() ); ( function() {} )(); [ function() {}() ]; ~ function() {}(); ! function() {}(); + function() {}(); - function() {}(); delete function() {}(); typeof function() {}(); void function() {}(); new function() {}(); new function() {}; var f = function() {}(); 1, function() {}(); 1 ^ function() {}(); 1 > function() {}(); // ... 

9、另外一種undefined

從來不需要聲明一個變量的值是undefined，因為JavaScript會自動把一個未賦值的變量置為undefined。所有如果你在代碼里這么寫，會被鄙視的

var data = undefined; ```` 但是如果你就是強迫症發作，一定要再聲明一個暫時沒有值的變量的時候賦上一個undefined。那你可以考慮這么做： ```javascript var data = void 0; // undefined 

void在JavaScript中是一個操作符，對傳入的操作不執行並且返回undefined。void后面可以跟()來用，例如void(0)，看起來是不是很熟悉？沒錯，在HTML里阻止帶href的默認點擊操作時，都喜歡把href寫成javascript:void(0)，實際上也是依靠void操作不執行的意思。

當然，除了出於裝逼的原因外，實際用途上不太贊成使用void，因為void的出現是為了兼容早起ECMAScript標准中沒有undefined屬性。void 0的寫法讓代碼晦澀難懂。

10、論如何優雅的取整

var a = ~~2.33 var b= 2.33 | 0 var c= 2.33 >> 0 

11、如何優雅的實現金錢格式化：1234567890 --> 1,234,567,890

用正則魔法實現：

var test1 = '1234567890' var format = test1.replace(/\B(?=(\d{3})+(?!\d))/g, ',') console.log(format) // 1,234,567,890 

非正則的優雅實現：

 function formatCash(str) { return str.split('').reverse().reduce((prev, next, index) => { return ((index % 3) ? next : (next + ',')) + prev }) } console.log(formatCash('1234567890')) // 1,234,567,890 

12、這個我服，還有這個你很機智

我服

while (1) {
alert('牛逼你把我關了啊')
}
你很機智，好一個障眼法

清除緩存： 清除緩存

13、逗號運算符

var a = 0; var b = ( a++, 99 ); console.log(a); // 1 console.log(b); // 99 

14、論如何最佳的讓兩個整數交換數值

常規辦法：

var a=1,b=2; a += b; b = a - b; a -= b; 

缺點也很明顯，整型數據溢出，對於32位字符最大表示數字是2147483647，如果是2147483645和2147483646交換就失敗了。
黑科技辦法：

a ^= b;
b ^= a;
a ^= b;

哈哈😄，看不懂的童鞋建議去補習一下C語言的位操作，我就不去復習了，以前學嵌入式時候學的位操作都忘了

15、實現標准JSON的深拷貝

var a = { a: 1, b: { c: 1, d: 2 } } var b=JSON.parse(JSON.stringify(a)) 

不考慮IE的情況下，標准JSON格式的對象蠻實用，不過對於undefined和function的會忽略掉。

16、不用Number、parseInt和parseFloat和方法把"1"字符串轉換成數字

哈哈，不准用強制類型轉換，那么就想到了強大了隱式轉換

var a =1 ; +a 

17、如何裝逼的寫出"hello world!"

滾動條很長哦😯

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居然能運行，牛逼的隱式轉換

18、parseInt(0.0000008) === 8

19、++[[]][+[]]+[+[]] == 10

強大的隱式轉換，23333

20、0.1 + 0.2 == 0.3

0.1 +0.2 == 0.3 竟然是不成立的。。。。所以這就是為什么數據庫存儲對於貨幣的最小單位都是分。

簡單說，0.1和0.2的二進制浮點表示都不是精確的，所以相加后不是0.3，接近（不等於）
0.30000000000000004。

所以，比較數字時，應該有個寬容值。ES6中這個寬容值被預定義了：Number.EPSILON。

21、最短的代碼實現數組去重

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

前不久面試阿里就問了這道題，哈哈，所以也寫上一下

22、用最短的代碼實現一個長度為m(6)且值都n(8)的數組

Array(6).fill(8)
這個夠短了吧，好像是當初哪里看到的一個面試題，就自己想到了ES6的一些API

23、短路表達式

條件判斷

var a = b && 1 // 相當於 if (b) { a = 1 } else { a = b } var a = b || 1 // 相當於 if (b) { a = b } else { a = 1 } 

24、JavaScript版迷宮

逃出迷宮，2333

25、取出一個數組中的最大值和最小值

var numbers = [5, 458 , 120 , -215 , 228 , 400 , 122205, -85411]; var maxInNumbers = Math.max.apply(Math, numbers); var minInNumbers = Math.min.apply(Math, numbers); 

26、將argruments對象轉換成數組

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

或者ES6：

var argArray = Array.from(arguments) 

27、javascript高逼格之Function構造函數

很多JavaScript教程都告訴我們，不要直接用內置對象的構造函數來創建基本變量，例如var arr = new Array(2); 的寫法就應該用var arr = [1, 2];的寫法來取代。

但是，Function構造函數（注意是大寫的Function）有點特別。Function構造函數接受的參數中，第一個是要傳入的參數名，第二個是函數內的代碼（用字符串來表示）。

var f = new Function('a', 'alert(a)');
f('jawil'); // 將會彈出窗口顯示jawil
這種方式可以根據傳入字符串內容來創建一個函數 是不是高大上？！

28、從一個數組中找到一個數，O(n)的算法，找不到就返回 null。

正常的版本:

function find (x, y) { for ( let i = 0; i < x.length; i++ ) { if ( x[i] == y ) return i; } return null; } let arr = [0,1,2,3,4,5] console.log(find(arr, 2)) console.log(find(arr, 8)) 

結果到了函數式成了下面這個樣子（好像上面的那些代碼在下面若影若現，不過又有點不太一樣，為了消掉if語言，讓其看上去更像一個表達式，動用了 ? 號表達式）：

//函數式的版本

const find = ( f => f(f) ) ( f => (next => (x, y, i = 0) => ( i >= x.length) ? null : ( x[i] == y ) ? i : next(x, y, i+1))((...args) => (f(f))(...args))) let arr = [0,1,2,3,4,5] console.log(find(arr, 2)) console.log(find(arr, 8)) 

如何讀懂並寫出裝逼的函數式代碼

最后奉勸大家一句：莫裝逼、白了少年頭