What this snippet does
Type safety extends to array mutations, preventing mixed types from slipping into collections.
Expected output
Compile Error: Argument of type 'string' is not assignable to parameter of 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
- Assigning a string to a number variableBasic Types · beginner
- Defining an array of numbersBasic Types · beginner
- Processing a list of user IDsBasic Types · beginner
- Declaring a fixed-length tupleBasic Types · beginner