is this a function or an object being returned?

Question

const {sum, subtract} = require('./math')



let result, expected
result = sum(3, 7)
expected = 10
expect(result).toBe(expected)


function expect(actual) {
  return {
    toBe(expected) {
      if (actual !== expected) {
        throw new Error(`${actual} is not equal to ${expected}`)
      }
    },
  }
}

is toBe{...} and object or a function?

It is used as a function when you call expect(result).toBe(expected).However, in the expect function definition it looks like an object because it doesn't have a function keyword. However objects do not accept parameters. Thank you in advance.

https://dev.to/sarah_chima/enhanced-object-literals-in-es6-a9d — SLaks, Dec 16 '18 at 01:26
@Li357 why can you create a function without declaring the keyword function? — Andrew Rivera, Dec 16 '18 at 01:26
@AndrewRivera methods and arrow functions don't use the keyword. — Andrew Li, Dec 16 '18 at 01:27
Your function is returning an object that has a property `toBe` which is a function. It's using a method shorthand to define the function. It's basically the same as `{ toBe: function(expected) {/*..etc */} }` — Mark, Dec 16 '18 at 01:27

score 0 · Answer 1 · answered Dec 16 '18 at 01:30

I think you are new to ES6 syntax, Search and read some article online.

Function expect is returning an object (return {}); That Object has a function called toBe(Its ES6 way of writing function inside object that you can omit keyword function).

Similarly inside ES6 classes there is no need to use the keyword function

is this a function or an object being returned?

1 Answers1