摘要：但是，構造函數注意是大寫的有點特別。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。

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，補充送那啥邀請碼。

本文秉承著：你看不懂是你SB，我寫的代碼就要牛逼。

"★★★★★☆☆☆☆☆".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

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

了解為什么請移步：一行能裝逼的JavaScript代碼

這個牛逼了

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

???，舅服你

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

[].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

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

解析請移步：js奇淫技巧1

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() {}();
// ...

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癥發作，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：

 var data = void 0; // undefined

void在JavaScript中是一個操作符，對傳入的操作不執行并且返回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，除了出于裝逼的原因外，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標準中沒有undefined屬性。void 0的寫法讓代碼晦澀難懂。

var a = ~~2.33

var b= 2.33 | 0

var c= 2.33 >> 0

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

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

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

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，對于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

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

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

哈哈，不準用強制類型轉換，那么就想到了強大了隱式轉換

var a =1 
+a

滾動條很長哦?

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居然能運行，牛逼的隱式轉換

強大的隱式轉換，23333

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于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（不等于）
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。

[...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

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

條件判斷

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

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

逃出迷宮，2333

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

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

或者ES6：

var argArray = Array.from(arguments)

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？！

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))

如何讀懂并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，2333。。。原文收錄在我的 GitHub博客 ( https://github.com/jawil/blog ) ，喜歡的可以關注最新動態，大家一起多交流學習，共同進步，以學習者的身份寫博客，記錄點滴。