How to save logs to a text file using JavaScript

Question

I am making a website, and I have Javascript code located directly in the HTML with the script tags. I want to log the IP addresses to a blank text file located in log/logfile.txt. I have a script to capture the time and IP address of the user, and here it is:

  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
   <script>
       $.get("https://ipinfo.io", function(response) {
           var ip = response.ip
       }, "json")
       var today = new Date();
       var date = today.getFullYear()+'-'+(today.getMonth()+1)+'-'+today.getDate();
       var time = today.getHours() + ":" + today.getMinutes() + ":" + today.getSeconds();
       var dateTime = date+' '+time;
       var data = response.ip+' Connected at '+dateTime;
       </script>

I want to write to the log file on my web server, but I don't know how. I've looked for similar question here but have found no answer. I've tried

const fs = require('fs') 

fs.writeFile('log/logfile.txt', data, (err) => { 
      
    if (err) throw err; 
}) 

And again, it doesn't work. Any help resolving this problem would be greatly apreciated.

Answer 1

JavaScript running in the browser cannot write to files on the server.

You need to send data to the server (typically this would be done by making an HTTP request; you're using jQuery already so you could use $.post for this).

Then you need to read the data from the request using server-side code and write it to the file. The code you've found is designed to run using Node.js. You could write a web server using Node.js (the Express.js framework is helpful for this) to handle this. If you don't want to use server-side JS (or if your web hosting only provides you with other programming language support) you can use any other language for the server-side portion of the program.

Answer 2

I want to write to the log file on my web server

JavaScript is a client side language; it runs on the computer running the browser not on the server. In order to update a log file on the server you'll need to eg perform an HTTP POST to send the data to some code on your server which will then save it.