javascript的一些技巧

一, 数值互换

1.1 定义一个变量

let  a = 1,
     b = 2,
     tmp = '';
     
     tmp = a;
     a = b;
     b = tmp;

1.2 算术运算

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

1.3 异或运算(会进行二进制转换)

let  a = 1,
     b = 2;
     
     a = a ^ b;
     b = a ^ b;
     a = a ^ b;

1.4 ES6语法

let a = 1,
    b = 2;
 
    [a, b] = [b, a];

1.5 数组特性转换

let a = 1,
    b = 2;
 
    a = [a, b];
    b = a[0];
    a = a[1];

1.6 数组加运算符(优先级)

let a = 1,
    b = 2;
    a = [b, b =a][0]

2,取整

1.3 ｜ 0 // 1 向下取整
-1.3 ｜ 0 // 1 向上取整

3, 判断奇偶数&1

let num1 = 2,
!(num &1) // false