What this snippet does
TypeScript catches type mismatches during compilation before they cause runtime errors.
Expected output
Compile Error: Type 'string' is not assignable to type 'number'.
Why practise typing this
Typing basic 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
- Declaring variables with primitive typesBasic Types · beginner
- Typing function parameters with primitivesBasic Types · beginner
- Defining an array of numbersBasic Types · beginner
- Processing a list of user IDsBasic Types · beginner
- Pushing a wrong type to a typed arrayBasic Types · beginner
- Declaring a fixed-length tupleBasic Types · beginner