What this snippet does
Symbol.for() registers Symbols in a global registry — two calls with the same key return the same Symbol unlike Symbol().
Expected output
true app.id false undefined
Why practise typing this
Typing symbols code builds muscle memory for the symbols and indentation JavaScript 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 JavaScript practice
- Symbol uniqueSymbols · intermediate
- Symbol keysSymbols · advanced
- well-known SymbolsSymbols · advanced
- let vs constVariables · beginner
- const configVariables · beginner
- const mutationVariables · beginner