你要的几个JS实用工具函数（持续更新）

/**
 * 封装fetch函数，用Promise做回调
 * @type {{get: (function(*=)), post: (function(*=, *=))}}
 */
const fetchUtil = {
    get: (url) => {
        return new Promise((resolve, reject) => {
            fetch(url, {
                method: 'GET',
                headers: {
                    'Content-Type': 'application/x-www-form-urlencoded',
                }
            }).then((response) => response.json()).then(response => {
                resolve(response);
            }).catch(err => {
                reject(new Error(err));
            });
        });
    },
    post: (url, params) => {
        return new Promise((resolve, reject) => {
            fetch(url, {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/x-www-form-urlencoded',
                },
                body: params
            }).then((response) => response.json()).then(response => {
                resolve(response);
            }).catch(err => {
                reject(new Error(err));
            });
        });
    }
};
export default fetchUtil;

import Fetch from "../util/FetchUtil.js";
    // post请求
    post(){
      let params = "";
      params += "phone=" + "xxxxxx" + "&password="+"123456";
      Fetch.post("https://carvedu.com/api/user/sms", this.params)
        .then(res => {
          console.log(res);
        })
        .catch(err => {
          console.log(err);
        });
    }
    // get请求
    get() {
      Fetch.get("https://carvedu.com/api/courses")
        .then(res => {
          console.log(res);
        })
        .catch(err => {
          console.log(err);
        });
    }

function getSystem(){
    const mac = /mac/i,
        linux = /linux/i,
        win = /win/i;
    const platform = navigator.platform.toLowerCase();
    if(mac.test(platform)){
        return 'MAC';
    } else if(win.test(platform)){
        return 'WIN';
    } else if(linux.test(platform)){
        return 'Linux';
    }
    return undefined;
}
const browser = { 
    versions:function(){ 
        let ret = 'xxSys';
        const u = navigator.userAgent;
        const isMobile = !!u.match(/AppleWebKit.*Mobile.*/),
            ios = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/),
            android = u.indexOf('Android') > -1 || u.indexOf('Adr') > -1;
        if(isMobile){
            if(ios) return 'IOS';
            if(android) return 'Android';
        } else {
            ret = getSystem() || ret;
        }
        return ret;
    }(),
};
export default browser;

import browser from "../util/browers.js"
console.log(browser.versions);

let startTime = new Date().getTime();
export const start = (v) =>{
  if(v==='reset'){
    return startTime = new Date().getTime();
  } else{
    return startTime;
  }
}

import {start} from "../util/Time.js"
click(){
  let userTime =  new Date().getTime()-start();
  start('reset');
}

export default {
    // 正则
    regExp:()=>{
      return {
        mPattern :/^1[345789]\d{9}$/, //手机号验证规则
        cP : /^[1-9]\d{5}(18|19|([23]\d))\d{2}((0[1-9])|(10|11|12))(([0-2][1-9])|10|20|30|31)\d{3}[0-9Xx]$/, // 身份证验证规则
        regCode : /^\d{4}$/ //验证码规则
        /*......*/
      }
    }
}

import regExp from '../util/regExp.js'
reg(){
      var value ="" // 手机号码举例
      console.log(regExp.regExp().mPattern.test(value));
},

export default {
  // 判断有无摄像头
    videoCheck:()=>{
      var deviceList = [];
      navigator.mediaDevices
        .enumerateDevices()
        .then(devices => {
          devices.forEach(device => {
            deviceList.push(device.kind);
          });
          if (deviceList.indexOf("videoinput") == "-1") {
            console.info("没有摄像头");
            return false;
          } else {
            console.info("有摄像头");
          }
        })
        .catch(function(err) {
          alert(err.name + ": " + err.message);
        });
    },
}

import videoCheck from '../util/videoCheck.js'
videoCheck.videoCheck();

export default {
    // 图片加载
    imgLoad:(src)=>{
      let bgImg = new Image();
      bgImg.src = src; // 获取背景图片的url
      bgImg.onerror = () => {
        console.log("img onerror");
      };
      bgImg.onload = () => {
        console.log("加载完成");
        return false
      };
    }
}

import imgLoad from '../util/imgLoad'
imgLoad.imgLoad('这里写图片的地址');

export default {
    getHtmlobj:(htmlobj)=>{
        var el = document.createElement('div');
        el.innerHTML = htmlobj;
        var tags = el.getElementsByTagName('img');
        var text = tags[0].getAttribute("src");
        return text;
      }
  }

import getHtmlobj from '../util/getHtmlobj';
  const htmlobj = '<div><p>标签</p><img src="ggg"/></div>';
  getHtmlobj(htmlobj);