@philiprehberger/type-check
v0.1.2429 downloadsMIT
Runtime type checking utilities with TypeScript type guards — typeof on steroids
$
npm install @philiprehberger/type-checkREADME
@philiprehberger/type-check
Runtime type checking utilities with TypeScript type guards — typeof on steroids
Installation
npm install @philiprehberger/type-check
Usage
Basic Guards
import { isString, isNumber, isPlainObject } from '@philiprehberger/type-check';
isString('hello'); // true
isString(42); // false
isNumber(3.14); // true
isNumber(NaN); // false
isPlainObject({ a: 1 }); // true
isPlainObject([]); // false
Type Narrowing
import { isString, isNumber } from '@philiprehberger/type-check';
function format(value: unknown): string {
if (isString(value)) {
return value.toUpperCase(); // TypeScript knows value is string
}
if (isNumber(value)) {
return value.toFixed(2); // TypeScript knows value is number
}
return String(value);
}
isEmpty
import { isEmpty } from '@philiprehberger/type-check';
isEmpty(''); // true
isEmpty([]); // true
isEmpty({}); // true
isEmpty(new Map()); // true
isEmpty(null); // true
isEmpty('hello'); // false
isEmpty([1, 2]); // false
isEmpty({ a: 1 }); // false
API
| Function | Returns true for |
|---|---|
isString(value) | string values |
isNumber(value) | number values (excludes NaN) |
isBoolean(value) | boolean values |
isBigInt(value) | bigint values |
isSymbol(value) | symbol values |
isFunction(value) | Functions |
isUndefined(value) | undefined |
isNull(value) | null |
isNullish(value) | null or undefined |
isPlainObject(value) | Plain objects ({}, Object.create(null)) |
isArray(value) | Arrays |
isTypedArray(value) | Typed arrays (Uint8Array, Float64Array, etc.) |
isDate(value) | Valid Date instances |
isRegExp(value) | RegExp instances |
isError(value) | Error instances (including subclasses) |
isMap(value) | Map instances |
isSet(value) | Set instances |
isPromise(value) | Promise instances or thenables with catch |
isIterable(value) | Objects with Symbol.iterator |
isAsyncIterable(value) | Objects with Symbol.asyncIterator |
isEmpty(value) | Empty strings, arrays, objects, maps, sets, or nullish |
Development
npm install
npm run build
npm test
Support
If you find this project useful: