What this snippet does
Object literals undergo excess property checking, failing if they contain properties not defined in the interface.
Expected output
Compile Error: Object literal may only specify known properties, and 'age' does not exist in type 'User'.
Why practise typing this
Typing objects and interfaces 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.
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