常用的js函数

获取url指定参数

function QueryString(val) {
  var uri = window.location.search;
  var re = new RegExp("[?&]" + val + "=([^&?]*)", "ig");
  return ((uri.match(re)) ? (uri.match(re)[0].substr(val.length + 2)) : null)
}

获取url所有参数

function getQueryObject(url) {
  url = url == null ? window.location.href : url
  const search = url.substring(url.lastIndexOf('?') + 1)
  const obj = {}
  const reg = /([^?&=]+)=([^?&=]*)/g
  search.replace(reg, (rs, $1, $2) => {
    const name = decodeURIComponent($1)
    let val = decodeURIComponent($2)
    val = String(val)
    obj[name] = val
    return rs
  })
  return obj
} 

查询数组中指定元素下标

function findArray(array, feature, all = true) {
  for (const index in array) {
    const cur = array[index];
    if (feature instanceof Object) {
      let allRight = true;
      for (const key in feature) {
        const value = feature[key];
        if (cur[key] === value && !all) return array[index];
        if (all && cur[key] !== value) {
          allRight = false;
          break;
        }
      }
      if (allRight) return array[index];
    } else {
      if (cur === feature) {
        return array[index];
      }
    }
  }
  return null;
}

获取昨天

function getYesterDate(time) {
  const date = time ? new Date(time) : new Date();
  date.setTime(date.getTime() - 24 * 60 * 60 * 1000);
  return date;
}

判断对象数组中是否存在指定键值对

function arrayIsExistKeyValue(arr, key, value) {
  if (arr.length > 0) {
    return arr.some(item => item[key] === value);
  }
  return false;
}

网络文件下载

'use strict';

const ProgressBar = require('progress');
const https = require('https');
const http = require('http');
const fs = require('fs');
const Path = require('path');
const URL = require('url');

/**
 * 下载单个文件
 * @param {String} fileUrl 网络文件路径
 * @param {String} path 文件存放位置
 * @param {String} fileName 文件名
 */
const downloadFile = (fileUrl, path, fileName) => {
  fileName = fileName ? fileName : Path.basename(fileUrl);
  path = path ? path : './';
  const stream = fs.createWriteStream(path + fileName);

  const url = URL.parse(fileUrl);
  let req = null;
  if (url.protocol === 'http:') req = http.request(url);
  if (url.protocol === 'https:') req = https.request(url);

  req.on('response', (res) => {
    const len = parseInt(res.headers['content-length'], 10);

    const bar = new ProgressBar(`downloading ${fileName} [:bar] :rate/bps size: ${len}KB :percent :etas`, {
      complete: '=',
      incomplete: '-',
      width: 100,
      total: len,
    })
  
    res.on('data', chunk => {
      bar.tick(chunk);
      stream.write(chunk, 'utf-8');
    })
  
    res.on('end', _ => {
      console.log('/n')
      stream.end();
    })

    res.on('error', err => {
      console.error(err);
    })
  })
  req.end();
}

/**
 * 下载多个文件
 * @param {String[]} fileUrls 网络文件路径数组
 * @param {String} path 文件存放位置
 */
const downloadFiles = (fileUrls, path) => {
  if (fileUrls && fileUrls.length === 0) throw new Error('fileUrls cannot be empty');
  path = path ? path : './';

  fileUrls.forEach(url => {
    downloadFile(url, path)
  })
}

module.exports = {
  downloadFile,
  downloadFiles,
}