What this snippet does
Any value outside the specified literal set will trigger a compile error.
Expected output
Compile Error: Type '"up"' is not assignable to type '"left" | "right"'.
Why practise typing this
Typing union and intersection 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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- Combining two object types with an intersectionUnion and Intersection Types · beginner
- Mixing mixins to create a LoggedUserUnion and Intersection Types · beginner
- Creating an impossible type intersectionUnion and Intersection Types · beginner