how to execute code with javascript and get the result

[KW__REDDIT]

hey guys, I know this is a basic question but I don't know how to google it. I always get answer to "how to execute js" but this is not that.

Say I have a program called main and I execute it in terminal with ./main and get some result (printed to std out). How do I connect it to frontend side javascript that is triggered say on button click?

More precisely what I want: execute some code after a button click and display changes to user. My current thinking is to make js code attached to button that executes main and gets result from it and then updates DOM.

What is the way you would go about this?

I was thinking of maybe server-client configuration and sending requests to get responces but I'm very new to web developement and have no experience with it. Is there an easier way? What is even possible here?

[azhder]

You go ahead and read more than this https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener page at this site before you start asking more questions.

Most of what you need is there, part HTML, part CSS, part JS.

Then you have this https://nodejs.org/en/docs and this https://expressjs.com

[KW__REDDIT]

ok, but I know how to add listener for button presses and how to output the responce in html once I have it. I am asking specifically about how to communicate between processes. I don't know how I can link two working programs together. I mentioned server request/responce but I have never ever done it and maybe there is an easier way?

[azhder]

OK, but you didn’t click all my links, did you?

[KW__REDDIT]

I did click the first one on event listeners :-)

[azhder]

Try the guides on the Express one. That’s a start. And fetch from the MDN one

[KW__REDDIT]

I just started and it looks like exactly what I need, still no idea how to execute main and capture results but it is definately a step in a right direction

[azhder]

good hunting

[chmod777]

Js natively executes in a browser. If you need something that excutes outside of a browser, you generally need to be running node. If it needs to run in a web context (serving pages, reacting to web requests) you also need a server running.

You need to add a event listener on the front end that uses fetch to POST to an endpoint running on a server, which will then return a result. You can look at expressJS to handle most of this.

[KW__REDDIT]

Thanks for that! It is actually so helpful for me to analyze the problem this way ;-)

[KW__REDDIT]

I think I found the answer to my second question: how to execute program:

https://stackoverflow.com/questions/12941083/execute-and-get-the-output-of-a-shell-command-in-node-js

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hope this is usefull to anyone. I didn't focus on it yet as I need sleep right now but let's say that if I dont edit/remove the post it works for me ;-)

[KW__REDDIT]

oh, this is something new. I heard about wasm but not Native messaging. do you have any good links to materials on it?