Add missing properties for optional parameters and optional properties

[golopot]

🔍 Search Terms

"add missing properties", "quick fix", "optional parameters", "optional property"

✅ Viability Checklist

• 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 isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
• This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

⭐ Suggestion

Offer "add missing properties" quick fix for optional parameters and optional properties.

📃 Motivating Example

type T = { t: string }
function f(arg?: T) {}
f({})
// expect quick fix "add missing property" to be available at `{}`

type U = { u?: { v: string } }
const u: U = { u: {} }
// expect quick fix "add missing property" to be available at `u`

Playground Link

💻 Use Cases

1. What do you want to use this for? better DX
2. What shortcomings exist with current approaches? manual input
3. What workarounds are you using in the meantime? manual input