What this snippet does
Implementing Symbol.iterator allows custom objects to work with for..of loops and the spread operator.
Expected output
[ 1, 2, 3 ]
Why practise typing this
Typing symbols & iterators 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 a unique symbolSymbols & Iterators · advanced
- Accessing symbol properties with string keysSymbols & Iterators · advanced
- Implementing a basic iterator interfaceSymbols & Iterators · advanced
- Custom collection iterator with done stateSymbols & Iterators · advanced
- Forgetting to return done: trueSymbols & Iterators · advanced
- Creating a basic generator functionSymbols & Iterators · advanced