Detailed explanation of express's middleware bodyParser_node.js

                                                                      function uploadFile(){
          var formData=new FormData();
            var files=document.getElementById("files").files;
            var file=files[0];
             formData.append("myfile",file);
            var xhr=new XMLHttpRequest();
                xhr.open("post","index.html",true);
                  xhr.onload= function (e) {
If(this.status==200)
document.getElementById("result").innerHTML=this.response;
             };
                 xhr.send(formData);
         }



Please select a file:

var express=require("express");
var fs=require("fs");
var app=express();
app.use(express.bodyParser());
app.get("/index.html", function (req,res) {
res.sendfile(__dirname "/1.html");
});
app.post("/index.html", function (req,res) {
var file=req.files.myfile;
fs.readFile(file.path, function (err,data) {
             if(err) res.send("File reading operation failed");
         else{
                          fs.writeFile(file.name,data, function (err) {
If(err) res.send("File writing operation failed.");
                     else res.send("File uploaded successfully");
              })
         }
});
});


app.listen(1337,"127.0.0.1", function () {
console.log("Start monitoring");
});

After starting the server, run the browser:

Select file:

The message "Upload successful" appears on the browser,

The files we uploaded are also available on the server side.

After clicking upload:

In addition, bodyParse can accept json data submitted by client ajax and process url.