What this snippet does
The third type parameter of AsyncGenerator dictates what type can be passed back into next(); passing 42 to a string TNext causes an error.
Expected output
Compile Error: Argument of type 'number' is not assignable to parameter of type 'string | PromiseLike<string>'.
Why practise typing this
Typing async iteration code builds muscle memory for the symbols and indentation TypeScript uses most, which prose-based typing tests never cover. DevType measures your words per minute and accuracy on this snippet and tracks the individual characters you mistype, so later lessons can target them.
More TypeScript practice
- Implementing an async iteratorAsync Iteration · advanced
- Consuming an async stream with for awaitAsync Iteration · advanced
- Attempting to use for-of on an async iteratorAsync Iteration · advanced
- Typing an async generator functionAsync Iteration · advanced
- Polling an API asynchronouslyAsync Iteration · advanced
- Declaring variables with primitive typesBasic Types · beginner