TypeScriptTips

Make bugs impossible.
One TypeScript tip at a time.

I like the tricks :) – Kasia

Type-safe pick

@RiccardoOdone•Suggest a tip•

You can prevent accessing undefined properties at compile time

const pick = (keys: string[], object: Record<string, any>): Record<string, any> =>
  keys.reduce((acc, key) => ({ ...acc, [key]: object[key] }), {})

pick(['name', 'age'], { name: 'riccardo', age: 18, color: 'pink' })
// { "name": "riccardo", "age": 18 }

pick(['hah!'], { name: 'riccardo', age: 18, color: 'pink' })
// ⛔️ { "hah!": undefined }

const pick = <R extends Record<string, unknown>>
  (keys: (keyof R)[], object: R): Record<string, unknown> =>
    keys.reduce((acc, key) => ({ ...acc, [key]: object[key] }), {})

pick(['name', 'age'], { name: 'riccardo', age: 18, color: 'pink' })
// { "name": "riccardo", "age": 18 }

pick(['hah!'], { name: 'riccardo', age: 18, color: 'pink' })
// ✅ Does not compile
Type-safe carouselDo not throwFilter using a type assertionUse precise typesType-safe string templatingEnumerating a union typeNumbers with unitsZero nullEnumerating statusesAnd typesAvoiding window as anyUse descriptive valuesCheck authorization with typesExtract union types from record typesKeep in sync with conditional typesType-safe pickPass arguments by namePick instead of duplicatingPrevent mutationsType aliasesModel with different typesPrefer static types over testsPush conditionals downType-level functionsCheck Authorization With Types (again)From Union to TupleLimit typesLaser-focused typesCallable typesPartial considered harmfulSatisfy typesWTH?!Parse, don't castNarrow typesFetch footgunModel with different types (2)Polymorphic typesParse, don't cast (again)Type-safe envObject vs Recordconst Type ParametersDigType checksExpand intellisenseNumbers with units (2)Unchecked indexed accessExtract instead of duplicating

TypeScriptTips

Crafted with 💛 by Riccardo