Having trouble checking when checkbox is checked

I’m trying to implement a like button into my site for some different pages and I’m using socket io so it updates for every user when the like button is pressed. I have a simple function of like() that emits liked which then makes a counter go up and displays on page. That’s not the issue though. I decided to make a checkbox so I can do something when the checkbox is unliked. I have a function for that too that works. I just can’t do something when it is unchecked. This is what I’m using to see if the checkbox is checked:

How to separate all of socket.io to a different file

Right now, I have app.js where I have my usual code and my socket.io code. But what I want to do is, separate every single code of socket.io into 1 different file and require that socket.io code from the different file into my main app.js. Is there any way to do it writing 2/3 lines of code into my app.js to require socket.io from a different file?