JavaScript : The Return

return.js

// You can set a variable to a function like this:
function myFunc(){
  
  var foo= 500;
  // foo is declared inside the function so it cannot be accessed outside of the function. 
  
  return foo;
}

var a = myFunc();
console.log(a); //500

returnToo.js

// If you declare the variable outside the function, you can then change the value inside the function, like so:
var foo = 0;

function myFunc(){
  foo= 500;
}

myFunc();
console.log(foo); //500

z-reference.md

Reference

https://www.quora.com/What-does-the-return-keyword-do-in-JavaScript/answer/Andrew-Webster-16