JSDoc support for String array to Object key

[imba97]

Suggestion

🔍 Search Terms

List of keywords you searched for before creating this issue. Write them down here so that others can find this suggestion more easily and help provide feedback.

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

JSDoc support for String array to Object key

📃 Motivating Example

/**
 * @template T
 * @param {T[]} obj
 * @returns {Readonly<{[T]: number}>}
 */
function Flags(obj) {
  const _obj = {}
  _.forEach(obj, (key, index) => {
    _obj[key] = 1 << index
  })
  return Object.freeze(_obj)
}

const TEST = Flags([
  'A',
  'B',
  'C',
  'D'
])

// We want to

// TEST.
//     -----------
//     | A       |
//     | B       |
//     | C       |
//     | D       |
//     -----------

💻 Use Cases

In the above example, I can use bit enumeration

/**
 * @param {number} enums
 * @param {number} flags
 */
function hasFlag(enums, flags) {
  return flags === (enums & flags)
}

cosnt test = TEST.A | TEST.C | TEST.D

console.log(hasFlag(test, TEST.A)) // true
console.log(hasFlag(test, TEST.B)) // false
console.log(hasFlag(test, TEST.C)) // true

[andrewbranch]

https://www.typescriptlang.org/play?ts=4.5.0-dev.20210910&filetype=js#code/PQKhCgAIUgBAXApgWwA4BsCGTIG8BOimAJgPYB26AnpAM7z4CW5A5gNoC6AvpACpQxYqTPkzI8vHqQBGAKwFxC8AK75ytPACUiZSlQA8uNgGlIzPm3LLk0xPg4cAXJCs27XAHxcBwcADNlcgBjeEYKSAAxLBZaAAoZWQBKPChIIIp6SAB9BMgAXjxvSGyAOj9SfABRTCCAC3i5ABpIWIBrRCpm5mJEAA9kvI8U4uKcuTZ2qg58yABGSH19M3Ie3tSuRNSlVXJIAHk5RBCywkQAL0RYsaTwb3B09Xg+SoBlXhmozBjY0EF4KlQiDwD3oPBAwBabFSAHIAILQxowgBCCJhAGFUcVoQARaHgDiJTbgXivXglcBAA

[imba97]

https://www.typescriptlang.org/play?ts=4.5.0-dev.20210910&filetype=js#code/PQKhCgAIUgBAXApgWwA4BsCGTIG8BOimAJgPYB26AnpAM7z4CW5A5gNoC6AvpACpQxYqTPkzI8vHqQBGAKwFxC8AK75ytPACUiZSlQA8uNgGlIzPm3LLk0xPg4cAXJCs27XAHxcBwcADNlcgBjeEYKSAAxLBZaAAoZWQBKPChIIIp6SAB9BMgAXjxvSGyAOj9SfABRTCCAC3i5ABpIWIBrRCpm5mJEAA9kvI8U4uKcuTZ2qg58yABGSH19M3Ie3tSuRNSlVXJIAHk5RBCywkQAL0RYsaTwb3B09Xg+SoBlXhmozBjY0EF4KlQiDwD3oPBAwBabFSAHIAILQxowgBCCJhAGFUcVoQARaHgDiJTbgXivXglcBAA

Thank you sir
Is it available only in v4.5.0?

[andrewbranch]

Yep—added in #45464

[imba97]

Thank you very much