What this snippet does
instanceof is the safest way to narrow an unknown caught error down to a standard Error object with a message property.
Expected output
fail
Why practise typing this
Typing error handling 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
- Extending the base Error classError Handling · intermediate
- Adding contextual data to custom errorsError Handling · intermediate
- Prototype chain breaking in transpiled ES5 errorsError Handling · intermediate
- Catch clause typed as unknownError Handling · intermediate
- Accessing message property on unknown errorError Handling · intermediate
- Throwing a string literalError Handling · intermediate