关于前端:JavaScript-常用函数

计算平均数

    const average = arr => arr.reduce((a, b) => a + b) / arr.length;

将 RGB 转为十六进制

const rgbToHex = (r, g, b) =>
    '#' + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);

计算两个日期相差的天数

const DayDiff = (firstDate, lastDate) =>
    Math.ceil(Math.abs(firstDate.getTime() - lastDate.getTime()) /
    1000 * 60 * 60 * 2
);

华氏度 / 摄氏度互相转换

# 华氏度转摄氏度
const fahrenheitToCelsius = item => ((item - 32) * 5) / 9;
# 摄氏度转华氏度
const celsiusToFahrenheit = item => (item * 9) / 5 + 32;

查问某个日期是否为工作日

const isWeekday = date => date.getDay() % 6 !== 0;

获取选定的文本

const getSelectedText = () => window.getSelection().toString();

文字复制到剪贴板

const copyText = async text => await navigator.clipboard.writeText(text);

查看设施类型

const judgeDeviceType = () =>
    /Android|webOS|iPhone|iPad|BlackBerry|IEMobile|OperaMini/i.test(navigator.userAgent)
    ? 'Mobile'
    : 'PC';

查看浏览器以后选项卡是否在后盾

const isTabActive = () => !document.hidden;

生成随机十六进制色彩值

const randomHexColor = () =>
    `#${Math.floor(Math.random() * 0xfffffff)
    .toString(16)
    .padEnd(6, '0')}`;

反转字符串

const reverse = str => str.split(‘’).reverse().join(‘’);

从 url 地址获取参数并转为对象

const getParameters = URL =>

JSON.parse(`{"${decodeURI(URL.split('?')[1])
    .replace(/"/g,'\\"')
    .replace(/&/g, '","')
    .replace(/=/g, '":"')}"}`
);

查看对象是否为空

const isEmpty = obj => Reflect.ownKeys(obj).length === 0 && obj.constructor === Object;

多重条件判断优化

# 同一个值比照不同的值
# name 为被比照的值
if (name ===’tom’|| name ===‘doy’|| name ===‘daiwei') {// ...}


# 升高耦合性的写法
const nameArr = [’tom’,‘doy’,‘daiwei’];
if (nameArr.includes(name)) {// ...}

生成随机数

# 随机数最大值为 max, 最小值为 min
const getRandomNum = (min = 0, max = 10) => {return Math.floor(Math.random() * (max - min + 1)) + min;
};

前端搜寻

# arr 要搜寻的数组，text 要搜寻的内容
# 含糊搜寻
const result = (arr, text) => arr.filter(item => item === text);

# 准确搜寻
const result = (arr, text) => arr.find(item => item === text);