How to implement ftp upload in javascript

In front-end development, sometimes you need to upload files to the server, and FTP is a commonly used file transfer protocol. Many projects also use FTP to upload and download files. Therefore, this article will introduce how to use JavaScript to implement FTP upload.

1. FTP Basics

FTP, File Transfer Protocol, is one of the most widely used file transfer protocols on the Internet. It can transfer files from a host on the Internet to another host. An FTP server is a special computer program that provides file transfer services.

The communication process of the FTP protocol is based on the TCP connection. The working method of FTP is mutual interactive data transmission between the client and the server. The FTP client connects to the FTP server and then transfers files or receives files. When transferring files, the FTP client transfers the data files to a specific directory in the FTP server, and the FTP server provides a secure method to store and access these files.

2. JavaScript to implement FTP upload

To use JavaScript to implement FTP upload, you need to use the FTP protocol to upload files. In the Web, we usually use XHR objects to handle file uploads, but XHR objects do not support the FTP protocol. Therefore, we need to use another network API in JavaScript-WebSocket API.

WebSocket API is a Web network API that supports two-way communication, and can pass messages between the browser and the server through the WebSocket object. Through WebSocket, the WebSocket client can send messages to the WebSocket server and receive messages sent back by the server.

In JavaScript, you can use the WebSocket API to implement FTP upload. The specific steps are as follows:

1. Create a WebSocket object

   When using WebSocket, you need to create a WebSocket object first. When creating a WebSocket object, we need to specify the address and port number of the WebSocket server.

   var socket = new WebSocket("ws://ftp.example.com:port");

2. Establish a connection

   After creating the WebSocket object, you need to establish a connection. The open event can be bound to the WebSocket object. When the WebSocket connection is successful, the open event will be triggered.

   socket.onopen = function() {
       // 连接成功
   };

3. Send FTP commands

   When the connection is established, you can send FTP commands to the FTP server through WebSocket. FTP commands are specific strings that can be sent to the FTP server through the send method of WebSocket. For example, the FTP command to upload a file is:

   socket.send("STOR filename");

   , where filename is the name of the file to be uploaded.

4. Send file data

   After sending the FTP command to the FTP server, the file data needs to be sent to the FTP server. You can use the FileReader API to read the file data to be uploaded, and then use WebSocket to send it to the FTP server. The code for uploading files is as follows:

   var fr = new FileReader();
   fr.readAsDataURL(file);
   fr.onload = function(e) {
       var data = e.target.result;
       socket.send(data);
   };

   Among them, file is the file object to be uploaded, and data is the file data.

5. Close the connection

   After completing the FTP upload, you need to close the WebSocket connection. You can bind the close event on the WebSocket object. When the WebSocket connection is closed, the close event will be triggered.

   socket.onclose = function() {
       // 连接关闭
   };

3. Summary

In this article, we introduced the FTP transfer protocol and the method of using JavaScript to implement FTP upload. Although the XHR object does not support the FTP protocol, FTP uploads can be implemented using the WebSocket API. Uploading files using WebSocket requires following a certain FTP command format and sending the file data to the FTP server.

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