microsoft / microsoft/TypeScript
Declare local variable as optional
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Description
Every time I type an undefinable variable, I think I typed something wrong:
let a: string | undefined;
Why do I think I did something wrong? It's because I never add undefined type to a union type as above except in variable declarations.
Don't you think it is time, introduce the optional operator to local variable declarations as well?
let a?: string;
The above syntax feel very natural and idiomatic typescript for me.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
The issue proposes allowing ? on local variable declarations instead of writing string | undefined; no file, test, or entry point is named. First determine the compiler areas and tests covering variable declaration syntax and type checking. Done means the syntax is accepted with well-defined semantics and the relevant behavior is covered by tests.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- compilers
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100