New rule suggestion: Object key names should only be quoted if necessary

[scouten]

Good:

let response = {id: 'foo', ok: true}

Bad:

let response = {'id': 'foo', 'ok': true}

[LinusU]

How do we feel about objects where some keys require quoting? I think it's more readable if they are all quoted:

const map = {
  'test-1': 73,
  'normal': 843,
  'other-key': 386,
  '1pass': 284,
  'sword': 83,
  'heavy-sword': 738
}

[yoshuawuyts]

I think quotes in keys should only be allowed for escaping, the same way we apply the rule to double quotes for strings.

[feross]

The reason that I initially did not enable this rule is because of the case that @LinusU points out.

As with all new rule proposals, the first step is to see how many repos would fail with it enabled.

[scouten]

@LinusU: That works, too. I guess I thought part of the purpose of this standard was to reduce wiggle room. I recently came across a case in my own code where I had been inconsistent in my use of quoting and it seemed like something that fit neatly into what standard was trying to accomplish.

[dcousens]

I think quote only if necessary is fine. It is consistent with our other idiosyncrasies (e.g semicolons).

[feross]

Adding the rule:

    "quote-props": [2, "as-needed"]

Results in the following failures:

1..423
# tests 423
# pass  388
# fail  35

which seems fairly high for a purely stylistic rule addition. Maybe we can add it once the rule is automatically fixable with ESLint's --fix feature?

[feross]

Let's re-open this issue once ESLint makes quote-props fixable. Right now there's nothing actionable for us to do.