20个你不得不知道的js位运算用法

let num = 4;
let multiplied = num << 1; // 结果为8
let divided = num >> 1; // 结果为2

let num = 7;
let isOdd = num & 1; // 结果为1，奇数

let a = 2, b = 3;
a ^= b;
b ^= a;
a ^= b; // a === 3, b === 2

let num = -6;
let abs = (num ^ (num >> 31)) - (num >> 31); // 结果为6

let num = 8;
let isPowerOfTwo = (num & (num - 1)) === 0; // 结果为true

let num = 21; // (10101)
num = (num >> 3) | (num << (32 - 3)); // 右轮转3位

let n = 5;
let result = 5 << 5; // 结果为160

// 使用掩码获取RGB颜色的红色分量
let color = 0xffeEDC;
let red = (color & 0xff0000) >> 16;

let flags = 5; // (101)
let mask = 2; // (010)
flags ^= mask; // 结果为7 (111)

let num = 4; // (100)
num |= 2; // 结果为6 (110)

let num = 15; // (1111)
num &= ~8; // 结果为7 (0111)

let num = 10;
num = ~num; // 结果为-11

let a = 10, b = 20;
let max = a - ((a - b) & ((a - b) >> 31));

let flag = 8; // (1000)
let isSet = flag & (1 << 3); // 结果为8，表示第3位被置位

let floatNum = 3.9;
let intNum = floatNum >> 0; // 结果为3

let color1 = 0xff00ff, color2 = 0x00ff00;
let mixed = (color1 & color2) + (((color1 ^ color2) & 0xfefefe) >> 1);

let num = 19;
let mod = num & (8 - 1); // 结果为3，相当于19 % 8

let array = 0;
array |= 1 << index; // 设置index位置为1
let isTrue = (array & (1 << index)) !== 0; // 检测index位置是否为1

let num = -48;
let opposite = ~num + 1; // 结果为48

let num = 13; // (1101)
let count = 0;
while(num) {
    count++;
    num &= num - 1; // 清除最低位的1
}
// 结果 count 为3