(!(~+[])+{})[--[~+""][+[]]*[~+[]] + ~~!+[]]+({}+[])[[~!+[]]*~+[]]
([][[]]+[])[+!![]]+([]+{})[!+[]+!![]]
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)}`)
Math.random().toString(16).substring(2) // 13位
Math.random().toString(36).substring(2) // 11位
( 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() {}();
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
var a = ~~2.33 //这种方法还可以将字符串转换成数字类型
var b= 2.33 | 0
var c= 2.33 >> 0
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
while (1) {
alert('牛逼你把我关了啊')
}
var a = 0;
var b = ( a++, 99 );
console.log(a); // 1
console.log(b); // 99
a ^= b;
b ^= a;
a ^= b;
var a = {
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。
var a =1 ;
+a
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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,0.1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。
[...new Set([1, "1", 2, 1, 1, 3])]
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)