「必须收藏」周末学到的 10 个 JS 实用的小技巧

const sleep = delay => {
    const start = new Date().getTime();
    while (new Date().getTime() < start + delay) {
       continue;
    };
};
console.log(1);
sleep(3000);
console.log(2);

const parseURL = (url = '') => {
    const res = new URL(url);
    res.queryParams = key => {
        if (key) {
           return res.searchParams.get(key)
        };
        const params = {};
        const paramGroup = res.search.replace(/^\?/,'').split('&');
        paramGroup.forEach(param => {
            const [key, val] = param.split('=');
            params[key] = val;
        });
        return params;
    };
    return res;
};
parseURL('https://www.example.com/a/b?c=1&d=2');

const getRate = (rate = 0) => '★★★★★☆☆☆☆☆'.slice(5 - rate, 10 - rate);
getRate(3);

// ｜ 取整
let num1 = 1.7;
num1 = num1 | 0;

// >> 取半
let num2 = 6;
num2 = num2 >> 1; // 3

// << 加倍

let num3 = 6;
num3 = num3 << 1; / / 12

// ^ 交换值
let num4 = 10;
let num5 = 20;

num4 ^= num5;
num5 ^= num4;
num4 ^= num5; // num4 === 2, num5 === 1

// & 判断奇数
let num6 = 10;
let num7 = 11;

num6 & 1 === 1; // true
num7 & 1 === 1; // false

// ~ 判断是否存在
const data = '123456';
const key = '3';
const keyIsExist = !!~data.indexOf(key); // true

// 是否 2 的整数幂
const isPowerOf2 = num => (num & (num - 1)) === 0;
isPowerOf2(8) // true
isPowerOf2(7) // false

const numberIsThousand = str => /^-?\d{1,3}(,\d{3})*(\.\d+)?$/.test(str);
numberIsThousand('100,000,000,000') // true
numberIsThousand('100,000,000,00') // false

const copyToClipboard = content => {
    const clipboardData = window.clipboardData;
    if (clipboardData) {
        clipboardData.clearData();
        clipboardData.setData('Text', content);
        return true;
    } else if (document.execCommand) {
        const el = document.createElement('textarea');
        el.value = content;
        el.setAttribute('readonly', '');
        el.style.position = 'absolute';
        el.style.left = '-9999px';
        document.body.appendChild(el);
        el.select();
        document.execCommand('copy');
        document.body.removeChild(el);
        return true;
    }
    return false;
};copyToClipboard('hello world');

const List = len => [...new Array(len).keys()];
const list = List(10); // [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

const type = data => {
      let toString = Object.prototype.toString;
      const dataType =
        data instanceof Element
          ? 'element' // 为了统一DOM节点类型输出
          : toString
              .call(data)
              .replace(/\[object\s(.+)\]/, '$1')
              .toLowerCase()
      return dataType
};

type({}); // object

const strIsRepeatThan2 = (str = '') => /^(?!.*(.).*\1{2})[\da-zA-Z].+$/.test(str);
strIsRepeatThan2('123456'); // true
strIsRepeatThan2('1234566'); // true
strIsRepeatThan2('12345666'); // false

const getCorrectNumber = (str = '') => /^(\d|[1-9]\d*)$/.test(str);
getCorrectNumber('0'); // true
getCorrectNumber('011'); // false
getCorrectNumber('101'); // true