What does return do in JavaScript?

return keyword stops the function and returns the given value from the function.

You can use return to either stop a function without returning a value:

function myFunction() {
  var a = 1;

  a++;

  if (a > 1) {
    return;
  }

  console.log("Cannot reach this line");
}

myFunction();

Or to stop a function and return a value:

function myFunction() {
  var a = 1;

  a++;

  if (a > 1) {
    return a;
  }

  console.log("Cannot reach this line");
}

var result = myFunction();

console.log(result); // 2