returning an object in JavaScript curly braces causing error

Question

I am currently working through codecademy JavaScript course and in Objects section I found this error. Section is about factory functions and the factory function takes two parameters. Factory function returns an object when called. After return statement when I press enter and start the curly braces on new line the program gives an error but when I move the opening curly brace back to same line as return keyword the error goes away. I have no idea why is this happening. Can anybody please put some light on what's happening with this code.

Code that gives syntax error

const robotFactory = (model, mobi) =>
{
  return 
  {
    model: model,
    mobi: mobi,
    beep()
    {
      console.log('Beep Boop');
    }
  }
};

const one = robotFactory('P-500', true);
console.log(one.model);

Code that does work

const robotFactory = (model, mobi) =>
{
  return {
    model: model,
    mobi: mobi,
    beep()
    {
      console.log('Beep Boop');
    }
  }
};

const one = robotFactory('P-500', true);
console.log(one.model);

Answer 1

JavaScript puts on implicit ;s. So with your following code:

const robotFactory = (model, mobi) =>
{
  return 
  {

JavaScript treats the above code as:

const robotFactory = (model, mobi) =>
{
  return;
  {

This is a Syntax Error. So you should never have any return statement on its own line.

More information: ECMAScript Automatic Semicolon Insertion, Understanding Automatic Semicolon Insertion in JavaScript, What are the rules for JavaScript's automatic semicolon insertion (ASI)?