What this snippet does
ReturnType<T> extracts the type returned by a function, useful for wrapping or mapping functions.
Expected output
1
Why practise typing this
Typing utility types 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
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- Mutating a Readonly type via aliasingUtility Types · intermediate