Html5 new XMLHttpRequest()监听附件上传进度

本文主要介绍new xmlhttprequest()监听附件上传进度，解决优化loading长时间加载，用户等待问题

一、存在问题

经测试发现，new xmlhttprequest()在附件上传请求中，wifi关闭切4g上传，上传进度不会持续；4g不关闭打开wifi会继续上传，但等待时间过长，实际上是4g在上传，倘若关闭4g网络，上传进度终止。

二、相关代码

2.1 html

<div class="process-wrapper" id="processwrap">
 <div class="process-face"></div>
 <img class="close-icon" id="closebtn" src="../../images/close.png" alt="">
 <div class="process">
  <div class="process-inner" id="processinner" style="width:50%"></div>
  <div class="process-value">
   <span>提交中...</span> 
   <span id="process">0%</span>
  </div>
 </div>
</div>

2.2 css样式

/* 附件上传进度条 */
.process-wrapper{
 -moz-user-select:none;
 position: fixed;
 left: 0;
 top: 0;
 bottom: 0;
 right: 0;
 z-index: 10000;
 display: none;
}
.process-face{
 width: 100%;
 height: 100%;
 background-color: #000;
 opacity: 0.7;
 position: fixed;
}
.close-icon{
 width: 26px;
 height: 26px;
 position: fixed;
 left: 50%;
 top: calc( 50% + 40px );
 transform: translate(-50%,-50%);
}
.process{
 width: 90%;
 height: 30px;
 background-color: #fff;
 border-radius: 30px;
 overflow: hidden;
 position: absolute;
 left: 50%;
 top: 50%;
 transform: translate(-50%,-50%);
 text-align: center;
 font-size: 14px;
 line-height: 30px;
 color: #999;
}
.process-inner{
 width: 100%;
 height: 30px;
 position: absolute;
 left: 0;
 top: 0;
 background-color: #0079c1;
 transition: 0.1s;
 z-index: -1;
}

2.3 js

(function(app, doc) {
 
 var $processwrap = document.getelementbyid("processwrap"),
 $closebtn = document.getelementbyid("closebtn"),
 xhr = new xmlhttprequest();
 doc.addeventlistener('netchange', onnetchange, false);
 function onnetchange() {
  if ($processwrap.style.display != "none") {
   $processwrap.style.display = "none";
   xhr.abort();
   mui.toast('网络中断请重试');
  }
 }
 dosend: function() {
   app.ajaxfile({  //封装好的ajax请求 
   url: "",
   data: formdata,
   xhr: xhr,
   success: function(r) {
    if (r == '1') {
     mui.toast("保存成功");
     // 上传成功逻辑处理
    } else {
     $processwrap.style.display = "none";
     mui.toast(app.neterror);
    }
   },
   error: function(r) {
    $processwrap.style.display = "none";
   },
   progress: function(e) {
    if (e.lengthcomputable) {
     var progressbar = parseint((e.loaded / e.total) * 100);
     if (progressbar < 100) {
      $progress.innerhtml = progressbar + "%";
      $processinner.style.width = progressbar + "%";
     }
    }
   },
   timeout:function(){
    $processwrap.style.display = "none";
   }

  });
 })
 mui.plusready(function() {
  $closebtn.addeventlistener("tap",function(){
   settimeout(function(){
    $processwrap.style.display = "none";
    xhr.abort();
   }, 400);
  })
 });
})(app, document);

三、app.js封装ajax请求

var $ajaxcount = 0;

window.app = {
 //ajaxfile超时时间
 filetimeout: 180000,
 ajaxfile: function(option) {
 $ajaxcount++; 
 var _ajaxcount = $ajaxcount;
 if (!option.error) {
  option.error = ajaxerror; // 请求失败提示
 }
 if (option.validateuserinfo == undefined) option.validateuserinfo = true;
 var xhr = option.xhr || new xmlhttprequest();
 xhr.timeout = app.filetimeout;
 xhr.open('post', app.getitem(app.localkey.url) + option.url, true);
 xhr.onreadystatechange = function() {
  if (xhr.readystate == 4 && xhr.status == 200) {
   var r = xhr.responsetext;
   if (r) {
    r = json.parse(r);
   }
   if (_ajaxcount == $ajaxcount) {
    option.success && option.success(r);
   }
  }
 }
 xhr.upload.onprogress = function (e) {
  option.progress(e);
 }
 xhr.onerror = function(e) {
  option.error(e); // 添加 上传失败后的回调函数
 }
 xhr.ontimeout = function(e){
  option.timeout(e);
  app.closewaiting();
  $.toast("请求超时,请重试");
  xhr.abort();
　　}
 xhr.send(option.data);
},
}

拓展：后端nodejs实现代码

const express = require("express");
const multer = require("multer");
const expressstatic = require("express-static");
const fs = require("fs");

let server = express();
let upload = multer({ dest: __dirname+'/uploads/' })
// 处理提交文件的post请求
server.post('/upload_file', upload.single('file'), function (req, res, next) {
  console.log("file信息", req.file);
  fs.rename(req.file.path, req.file.path+"."+req.file.mimetype.split("/").pop(), ()=>{
    res.send({status: 1000})
  })
})

// 处理静态目录
server.use(expressstatic(__dirname+"/www"))
// 监听服务
server.listen(8080, function(){
  console.log("请使用浏览器访问 http://localhost:8080/")
});

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