What is Function run in netlify?

According to the pricing for the netlify-functions used, it will be free upto 125k runs of the function.

So my concern is, how will be function consider as I am working with express.js and our project is developed in express.js and we want to convert it into lambda-function so only app.js file should be added into function directory or all js files will needs to add into functions directory for converting to lambda-function?

Note: functions directory am talking about is YOUR_BASE_DIRECTORY/netlify/functions mentioned in this path in the document.

Every time your Function is invoked, it would be counted as a Function run. If your app.js is invoked 100 times, that’s 100 invocations.

So, I just need to convert the app.js file to be lambda function in order to deploy project on netlify?

Also, the question is, will I need to all the js files present convert to lambda function or only app.js file (main file where the app starts ) need to convert to lambda function in order to make our project worked ?
@hrishikesh

Hey @Amarparihar,

Taking a step back, it appears to me that you’re going to be using Netlify solely to deploy an Express.js app. While you can do that, I’m not sure how well that’s going to scale.

About your actual question, I can’t comment a lot without actually seeing your project. In my Express.js-based Functions, I have only a single app.js that does the work. I don’t use any other JS files as you mention, so I’m not sure what they’re doing in your project.