JavaScript function that returns an object

Question

This function is supposed to return an object, however, the construction used below is unfamiliar to me. How does this function work?

function expect(value) {
  return {
    toBe: exp => console.log(success)
  }
}

Answer 1

This is a standard JavaScript function:

function(parameter1, parameter2) {
    return returnVal;
}

But the object that is being returned looks like this:

{
    toBe: exp => console.log(success)
}

Which is an object containing an ES6 arrow function, and can be alternatively expressed like so (a direct translation to an ES5 function):

{
    toBe: function(exp) { 
        return console.log(success);
    }
}

Read here for more information on ES6 arrow function notation.