原文地址：https://zhuanlan.zhihu.com/p/28937831

Javascript是一门很吊的语言 \n
本文秉承着：你看不懂是你SB，我写的代码就要牛逼。\n\n

1.单行写一个评级组件

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

定义一个变量率是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\n\n## 2.如何装逼用代码骂别人SB

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

3.如何用代码优雅的证明自己NB

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

4.JavaScript错误处理的方式的正确姿势

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

5.从一行代码里面学点JavaScript

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

翻译成正常语言就是这样的

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

Math.random().toString(16).substring(2) 
Math.random().toString(36).substring(2) 

7.(10)"toString" === "10"

8.匿名函数自执行

这么多写法你选择哪一种？

( 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

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：

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

var a = ~~2.33
var b= 2.33 | 0
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：

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

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

非正则的优雅实现：

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.这个我服，还有这个你很机智

while (1) {
    alert('牛逼你把我关了啊')
}

好一个障眼法

<a href="javascript:alert('清除成功');">清除缓存</a>

13.逗号运算符

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

14.论如何最佳的让两个整数交换数值

常规办法：

var a=1,b=2;
a += b;
b = a - b;
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：

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

15.实现标准JSON的深拷贝

    a: 1,
    b: { c: 1, d: 2 }
}
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

var a =1 
+a

17.如何装逼的写出"hello world!"

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牛逼的隐式转换

18. parseInt(0.0000008) === 8

19. ++[[]][+[]]+[+[]] == 10

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。
1.简单说，0.1和0.2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

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

22. 用最短的代码实现一个长度为m(6)且值都n(8)的数组

Array(6).fill(8)

23. 短路表达式

条件判断

var a = b && 1
// 相当于 
if (b) {
    a = 1
} else {
    a = b
}
var a = b || 1
// 相当于
if (b) {
    a = b
} else {
    a = 1
}

24. JavaScript版迷宫

25. 取出一个数组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、将argruments对象转换成数组

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

或者ES6：

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）。

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

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))

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）：

//函数式的版本
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))