What this snippet does
When the contextual type is a union of function types, TypeScript cannot contextually type the parameter, requiring explicit annotation.
Expected output
Compile Error: Parameter 'x' implicitly has an 'any' type.
Why practise typing this
Typing contextual typing 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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- Declaring variables with primitive typesBasic Types · beginner
- Typing function parameters with primitivesBasic Types · beginner
- Assigning a string to a number variableBasic Types · beginner