This latest post after so many days. Just working on a project so writing less but yea from now on will be regular. Exporting functions in JavaScript is a fundamental thing you should know for any type of projects it's just important.

Generally, we code to function as

function sum(f, b) {  
  return f + b  
}  

You make available for other files to use this function as
by this command

export default sum  

We called this as default export

The files that need the function exported will bring in it using this following syntax:

import sum from 'filename'

That's It!