microsoft / microsoft/TypeScript

Provide refactor to convert `[].forEach` to `for`/`for of` (And convert back)

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#44,162 3 comments 1 reaction 0 assignees View on GitHub

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Description

Suggestion

🔍 Search Terms

refactor, iterator, for

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

Provide refactor to convert [].forEach to for/for of (And convert back)

📃 Motivating Example

[].forEach((value, index) => {
  console.log(value, index)
})

// to

var arr = []
for (let index = 0; index < arr.length, index++) {
  let value = arr[index]

  console.log(value, index)
}


// or

for (let index of []) {
 console.log(value) // disallow index here
}

💻 Use Cases

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

No repository files, tests, or entry points are named; start by reviewing the suggestion and its examples. Clarify the supported conversions, scope, and behavior before locating the relevant TypeScript refactor entry point. Done means an agreed proposal with coverage for both conversion directions.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, typescript
Domain
tooling
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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