What this snippet does
The instanceof guard checks an object's prototype chain, narrowing it to a specific class.
Expected output
A
Why practise typing this
Typing type guards 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
- Narrowing a union with typeofType Guards · beginner
- Processing dynamic input based on typeofType Guards · beginner
- Using incorrect casing in typeof checksType Guards · beginner
- Handling specific error subclassesType Guards · beginner
- Using instanceof on primitive stringsType Guards · beginner
- Narrowing object types with the in operatorType Guards · beginner