avoid-wrapper-types
Avoid Object Wrapper Types (String, Number, Boolean, Symbol, BigInt)
Overview
Use lowercase primitive types, never uppercase wrapper types.
JavaScript has primitive types (string, number, boolean) and object wrapper types (String, Number, Boolean). TypeScript has types for both, but you should almost never use the wrapper types.
When to Use This Skill
- Typing any primitive value
- Seeing errors about wrapper type mismatches
- Understanding why
String !== string - Working with methods on primitives
The Iron Rule
ALWAYS use lowercase: string, number, boolean, symbol, bigint
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11