Why should we used a square bracket when using a calculated property for an object?

Asked Dec 25 '20 at 18:33

Active Dec 25 '20 at 18:33

Viewed 31 times

I saw in some lecture the following code:

   const weekdays = ['mon', 'tue', 'wed', 'thu', 'fri', 'sat', 'sun'];
const openingHours = {
  [weekdays[3]]: {
    open: 12,
    close: 22,
  },
  [weekdays[4]]: {
    open: 11,
    close: 23,
  },
  [weekdays[5]]: {
    open: 0, // Open 24 hours
    close: 24,
  },
};

I can't understand why we need to wrap weekdays[i] with a square brackets? Can someone explain me?

asked Dec 25 '20 at 18:33

Eitanos30

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1

Because if you don't, the syntax will be invalid, since dynamic property names require `[]`s around them – CertainPerformance Dec 25 '20 at 18:35
You don't need too, you could just remove weekdays array. Not sure why to use a const array for keys here, seems a bit pointless. – Keith Dec 25 '20 at 18:37
@Keith, it is an example from a course i am watching – Eitanos30 Dec 25 '20 at 18:42
Try running it without the `[]` and see the error thrown – charlietfl Dec 25 '20 at 18:43
@charlietfl i got: ',' expected.ts(1005) – Eitanos30 Dec 25 '20 at 18:49
@CertainPerformance, and also ' sign is required? – Eitanos30 Dec 25 '20 at 18:49
By the way, it is closed with an example that is **so not relevant** to my question – Eitanos30 Dec 25 '20 at 18:50
The only place `'` is being used is for the string delimiters for `weekdays` array, so yeah, I guess it's required there? – CertainPerformance Dec 25 '20 at 18:51
Does a dynamic property inside [] brackets must be from a string type? – Eitanos30 Dec 25 '20 at 18:53

Why should we used a square bracket when using a calculated property for an object?

0 Answers0