Allow non-null assertion operator on destructuring

🔍 Search Terms

destructuring non null assertion operator

✅ 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

Allow the non-null assertion post-fix operator to be used in destructuring assignments

📃 Motivating Example

I was destructuring an object with a long name, but I couldn't do so because I also needed to assert it wasn't null, and this is not currently allowed

const { veryVeryVeryLongPropertyName! } = obj;

So I had to do this

const veryVeryVeryLongPropertyName = obj.veryVeryVeryLongPropertyName!;

💻 Use Cases

What do you want to use this for?

To avoid having to specify the name twice

What workarounds are you using in the meantime?

// Workaround: Short name
// Shortcoming: Not what I actually wanted to do
const temp = obj.veryVeryVeryLongPropertyName!;

// Workaround: Default `never` value
// Shortcoming: Verbose
const { veryVeryVeryLongPropertyName = undefined! } = obj;

Start with the issue's destructuring examples and the stated constraint that emitted JavaScript must not change. Review the compiler's handling of non-null assertions and destructuring assignments, then establish the required design and tests; done means the proposed syntax is accepted without changing runtime output.