摘要：但是，構(gòu)造函數(shù)注意是大寫的有點(diǎn)特別。構(gòu)造函數(shù)接受的參數(shù)中，第一個(gè)是要傳入的參數(shù)名，第二個(gè)是函數(shù)內(nèi)的代碼用字符串來(lái)表示。

Javascript是一門很吊的語(yǔ)言，我可能學(xué)了假的JavaScript，哈哈，大家還有什么推薦的，補(bǔ)充送那啥邀請(qǐng)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(gè)變量rate是1到5的值，然后執(zhí)行上面代碼，看圖

才發(fā)現(xiàn)插件什么的都弱爆了

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

了解為什么請(qǐng)移步：一行能裝逼的JavaScript代碼

這個(gè)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(yǔ)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(lái)在瀏覽器控制看看：something magic happens

具體分析請(qǐng)參見這篇文章：從一行代碼里面學(xué)點(diǎn)JavaScript

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

解析請(qǐng)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(lái)不需要聲明一個(gè)變量的值是undefined，因?yàn)镴avaScript會(huì)自動(dòng)把一個(gè)未賦值的變量置為undefined。所有如果你在代碼里這么寫，會(huì)被鄙視的

var data = undefined;

但是如果你就是強(qiáng)迫癥發(fā)作，一定要再聲明一個(gè)暫時(shí)沒有值的變量的時(shí)候賦上一個(gè)undefined。那你可以考慮這么做：

 var data = void 0; // undefined

void在JavaScript中是一個(gè)操作符，對(duì)傳入的操作不執(zhí)行并且返回undefined。void后面可以跟()來(lái)用，例如void(0)，看起來(lái)是不是很熟悉？沒錯(cuò)，在HTML里阻止帶href的默認(rèn)點(diǎn)擊操作時(shí)，都喜歡把href寫成javascript:void(0)，實(shí)際上也是依靠void操作不執(zhí)行的意思。

當(dāng)然，除了出于裝逼的原因外，實(shí)際用途上不太贊成使用void，因?yàn)関oid的出現(xiàn)是為了兼容早起ECMAScript標(biāo)準(zhǔn)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(shí)現(xiàn)：

var test1 = "1234567890"
var format = test1.replace(/B(?=(d{3})+(?!d))/g, ",")

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

非正則的優(yōu)雅實(shí)現(xiàn)：

 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(guān)了啊")
}

你很機(jī)智，好一個(gè)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(guī)辦法：

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

缺點(diǎn)也很明顯，整型數(shù)據(jù)溢出，對(duì)于32位字符最大表示數(shù)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(bǔ)習(xí)一下C語(yǔ)言的位操作，我就不去復(fù)習(xí)了，以前學(xué)嵌入式時(shí)候?qū)W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(biāo)準(zhǔn)JSON格式的對(duì)象蠻實(shí)用，不過(guò)對(duì)于undefined和function的會(huì)忽略掉。

哈哈，不準(zhǔn)用強(qiáng)制類型轉(zhuǎn)換，那么就想到了強(qiáng)大了隱式轉(zhuǎn)換

var a =1 
+a

滾動(dòng)條很長(zhǎng)哦?

([]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+(!![]+[])[+[]]+([][[]]+[])[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]])())[+[]]+([][[]]+[])[!+[]+!![]+!![]]+(![]+[])[!+[]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+([][[]]+[])[+[]]+([][[]]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(![]+[])[!+[]+!![]+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+([]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+(!![]+[])[+[]]+([][[]]+[])[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]])())[!+[]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]])()([][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(![]+[])[!+[]+!![]+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+([]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+(!![]+[])[+[]]+([][[]]+[])[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]])())[!+[]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]])()(([]+{})[+[]])[+[]]+(!+[]+!![]+!![]+!![]+!![]+!![]+!![]+[])+(!+[]+!![]+!![]+!![]+!![]+!![]+!![]+[]))+([]+{})[+!![]]+(!![]+[])[+!![]]+(![]+[])[!+[]+!![]]+([][[]]+[])[!+[]+!![]]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+([][[]]+[])[+[]]+([][[]]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(![]+[])[!+[]+!![]+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+([]+[][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(!![]+[])[+[]]+([]+{})[+!![]]+(!![]+[])[+!![]]]((!![]+[])[+!![]]+([][[]]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+([][[]]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]+!![]+!![]]+(![]+[])[!+[]+!![]]+([]+{})[+!![]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+(+{}+[])[+!![]]+(!![]+[])[+[]]+([][[]]+[])[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]])())[!+[]+!![]+!![]]+([][[]]+[])[!+[]+!![]+!![]])()([][(![]+[])[!+[]+!![]+!![]]+([]+{})[+!![]]+(!![]+[])[+!![]]+(!![]+[])[+[]]][([]+{})[!+[]+!![]+!![]+!![]+!![]]+([]+{})[+!![]]+([][[]]+[])[+!![]]+(![]+[])[!+[]+!![]+!![]]+(!![]+[])[+[]]+(!![]+[])[+!![]]+([][[]]+[])[+[]]+([]+{})[!+[]+!![]+!![]+!![]+!![]]+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居然能運(yùn)行，牛逼的隱式轉(zhuǎn)換

強(qiáng)大的隱式轉(zhuǎn)換，23333

0.1 +0.2 == 0.3 竟然是不成立的。。。。所以這就是為什么數(shù)據(jù)庫(kù)存儲(chǔ)對(duì)于貨幣的最小單位都是分。

簡(jiǎn)單說(shuō)，0.1和0.2的二進(jìn)制浮點(diǎn)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(shù)字時(shí)，應(yīng)該有個(gè)寬容值。ES6中這個(gè)寬容值被預(yù)定義了：Number.EPSILON。

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

前不久面試阿里就問(wèn)了這道題，哈哈，所以也寫上一下

Array(6).fill(8)

這個(gè)夠短了吧，好像是當(dāng)初哪里看到的一個(gè)面試題，就自己想到了ES6的一些API

條件判斷

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

var a = b || 1
    // 相當(dāng)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(nèi)置對(duì)象的構(gòu)造函數(shù)來(lái)創(chuàng)建基本變量，例如var arr = new Array(2); 的寫法就應(yīng)該用var arr = [1, 2];的寫法來(lái)取代。

但是，F(xiàn)unction構(gòu)造函數(shù)（注意是大寫的Function）有點(diǎn)特別。Function構(gòu)造函數(shù)接受的參數(shù)中，第一個(gè)是要傳入的參數(shù)名，第二個(gè)是函數(shù)內(nèi)的代碼（用字符串來(lái)表示）。

var f = new Function("a", "alert(a)");
f("jawil"); // 將會(huì)彈出窗口顯示jawil

這種方式可以根據(jù)傳入字符串內(nèi)容來(lái)創(chuàng)建一個(gè)函數(shù) 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(jié)果到了函數(shù)式成了下面這個(gè)樣子（好像上面的那些代碼在下面若影若現(xiàn)，不過(guò)又有點(diǎn)不太一樣，為了消掉if語(yǔ)言，讓其看上去更像一個(gè)表達(dá)式，動(dòng)用了 ? 號(hào)表達(dá)式）：

//函數(shù)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(shù)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(guān)注最新動(dòng)態(tài)，大家一起多交流學(xué)習(xí)，共同進(jìn)步，以學(xué)習(xí)者的身份寫博客，記錄點(diǎn)滴。