Add extract to parameter refactoring for JS/TS in vscode

Search Terms

Suggestion

Add a refactoring to extract to parameter for JS/TS

e.g.

for

const fangler = () => {
  return {
    someProperty: [
      "a", "b"
    ]
  }
}

the extract to parameter refactoring would change to

const fangler = (secondItem) => {
  return {
    someProperty: [
      "a", secondItem
    ]
  }
}

and populate each existing call site with the extracted value (in this example "b")

Use Cases

It is a common refactoring when you discover that a previously fixed value should instead be provided by a caller

Examples

e.g. in the case where I went looking for it code in a Lambda function that created a fixed header had to start providing a varying value depending on context and the easiest refactoring was to extract the currently fixed value as a parameter so that the callers that would vary it could do without breaking other callers

see https://twitter.com/mattbierner/status/1234920525543002113

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, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

Start by reviewing the existing JavaScript/TypeScript refactoring support in the VS Code integration and the example behavior described in the issue. Define how an extracted expression becomes a parameter and how every existing call site receives the original value; done means the refactoring works for both JS and TS without changing unrelated runtime behavior.