Detailed explanation of Ajax and node.js multer to implement file upload function

As a node beginner, I have recently been working on a chat software that supports registration, login, online single and multi-person chat, emoticon sending, various file upload and download, adding and deleting friends, chat record saving, notification sound switch, background For image switching, games and other functions, the multer module was used. After various document searches and demo examples, I finally successfully implemented the single file upload function, which supports uploading of most file formats and displays it on the web page at the same time. This article mainly introduces Ajax cooperation. Node js multer implements the file upload function. Friends who need it can refer to it. I hope it can help everyone.

Effect

Does it feel like WeChat is instantly visible? Yes, it is based on the web version of WeChat.

To achieve the overall effect, it must be done with css and html. I am a front-end beginner and it is my first time to post a blog. I am really anxious. In the near future, I will put the code on github. Interested friends can take a look

Go directly to the code below, light abuse

Configuration

Installation

Install multer directly through the cmd command window

npm install multer -save

Server code

//引入http
const http=require("http");
//引入express
const express=require("express");
//引入multer
const multer=require("multer");
//创建服务器，绑定监听端口
var app=express();
var server=http.createServer(app);
server.listen(8081);
//建立public文件夹，将HTML文件放入其中，允许访问
app.use(express.static("public"));
//文件上传所需代码
//设置文件上传路径和文件命名
var storage = multer.diskStorage({
  destination: function (req, file, cb){
    //文件上传成功后会放入public下的upload文件夹
    cb(null, './public/upload')
  },
  filename: function (req, file, cb){
    //设置文件的名字为其原本的名字，也可以添加其他字符，来区别相同文件，例如file.originalname+new Date().getTime();利用时间来区分
    cb(null, file.originalname)
  }
});
var upload = multer({
  storage: storage
});
//处理来自页面的ajax请求。single文件上传
app.post('/upload', upload.single('file'), function (req, res, next) {
  //拼接文件上传后的网络路径，
  var url = 'http://' + req.headers.host + '/upload/' + req.file.originalname;
  //将其发回客户端
  res.json({
    code : 1,
    data : url
  });
  res.end();
});

Client code

nbsp;html>


  <meta>
  <title></title>
  <!--依托于jquery-->
  <script></script>


  <p>
    <label>file</label>
    <input>
  </p>
<script>
      var file=$("#file")[0];
      //这里使用的是onchange事件，所以当你选择完文件之后，就触发事件上传
      file.onchange=function(){
        //创建一个FormDate
        var formData=new FormData();
        //将文件信息追加到其中
        formData.append(&#39;file&#39;,file.files[0]);
        //利用split切割，拿到上传文件的格式
        var src=file.files[0].name,
            formart=src.split(".")[1]; 
        //使用if判断上传文件格式是否符合                                                          
                                                              if(formart=="jpg"||formart=="png"||
        formart=="docx"||formart=="txt"||
        formart=="ppt"||formart=="xlsx"||
        formart=="zip"||formart=="rar"||
        formart=="doc"){
        //只有满足以上格式时，才会触发ajax请求
          $.ajax({
            url: &#39;/upload&#39;,
            type: &#39;POST&#39;,
            data: formData,
            cache: false,
            contentType: false,
            processData: false,
            success: function(data){
            //上传成功之后，返回对象data         
              if(data.code>0){
                var src=data.data;
                    //利用返回值src 网络路径，来实现上传文档的下载    
                    if(formart=="docx"||formart=="txt"||formart=="doc"){
                    //结合css样式，实现显示图标
                  var className="docx";
                    //拼接html，生成到页面上去  
                  var msg=`<a href="${src}" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ><i class="${className}">`;
                }else if(formart=="ppt"){
            //PPT 格式
                    className="ppt";
                  msg=`<a href="${src}" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ><i class="${className}">`;
                }else if(formart=="xlsx"){
            //xlsx 格式
                    className="xlsx";
                  msg=`<a href="${src}" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ><i class="${className}">`;
          }else if(formart=="zip"||formart=="rar"){
          //zip || rar 格式
                    className="zip";
                  msg=`<a href="${src}" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ><i class="${className}">`;
                }else{
          //所有的图片格式      
                  msg=`<a href="javascript:;" rel="external nofollow" class="picCheck"><img  src="/static/imghwm/default1.png"  data-src="${src}"  class="lazy"   alt="Detailed explanation of Ajax and node.js multer to implement file upload function" >`;
                }
                // 这里将msg 追加到你要显示的区域 
              }
            } 
         //不满足上传格式时 
        }else{
          alert("文件格式不支持上传")
        }
      }
</script>

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