What does return do in JavaScript? The return keyword explained

The return keyword in JavaScript is a keyword to build a statement that ends JavaScript code execution. For example, suppose you have the following code that runs two console logs:

console.log("Hello");

return;

console.log("How are you?");

You’ll see that only “Hello” is printed to the console, while “How are you?” is not printed because of the return keyword. In short, the return statement will always stop any execution in the current JavaScript context, and return control to the higher context. When you use return inside of a function, the function will stop running and give back control to the caller.

The following function won’t print “Hi from function” to the console because the return statement is executed before the call to log the string. JavaScript will then give back control to the caller and continue code execution from there:

function fnExample() {
  return;
  console.log("Hi from function");
}

fnExample(); // nothing will be printed
console.log("JavaScript");
console.log("Continue to execute after return");

You can add an expression to the return statement so that instead of returning undefined, the value that you specify will be returned.

Take a look at the following code example, where the fnOne() function just return without any value, while fnTwo() returns a number 7:

function fnOne() {
  return;
}

function fnTwo() {
  return 7;
}

let one = fnOne();
let two = fnTwo();

console.log(one); // undefined
console.log(two); // 7

In the code above, the values returned from the return statement by each function are assigned to variables one and two. When return statement will give back undefined by default.

You can also assign a variable to the return statement as follows:

function fnExample() {
  let str = "Hello";
  return str;
}

let response = fnExample();
console.log(response); // Hello

And that’s all about the return keyword in JavaScript. You can combine the return statement and conditional if..else block to control what value returned from your function.

In the following example, the function will return “Banana” when number === 1 else it will return “Melon”:

function fnFruit(number) {
  if (number === 1) {
    return "Banana";
  } else {
    return "Melon";
  }
}

let fruit = fnFruit(1);
console.log(fruit); // "Banana"