What this snippet does
'any' opts out of checking, 'unknown' is a safe top type requiring narrowing, and 'never' is the bottom type that cannot hold a value.
Expected output
1 1 undefined
Why practise typing this
Typing type system limits 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
- Using never to filter union typesType System Limits · advanced
- Assigning values to a never variableType System Limits · advanced
- Deeply nested type instantiationType System Limits · advanced
- Exceeding tuple recursion limitsType System Limits · advanced
- Infinite conditional type distributionType System Limits · advanced
- Defining a circular type referenceType System Limits · advanced