Essential utilities for TypeScript projects

Ideas for additional essential utilities welcome. Type-only utilities belong in type-fest.

npm install ts-extras

import {isDefined} from 'ts-extras';
[1, undefined, 2].filter(isDefined);
//=> [1, 2]

General

• asWritable - Cast the given value to be Writable.
• safeCastTo - Cast a value to the given type safely.

Type guard

• isDefined - Check whether a value is defined (not undefined).
• isPresent - Check whether a value is present (not null or undefined).
• isEmpty - Check whether an array is empty.
• isInfinite - Check whether a value is infinite.
• assertDefined - Assert that the given value is defined, meaning it is not undefined.
• assertPresent - Assert that the given value is present (non-nullable), meaning it is neither null or undefined.
• assertError - Assert that the given value is an Error.

Improved builtin

• arrayIncludes - An alternative to Array#includes() that properly acts as a type guard.
• setHas - An alternative to Set#has() that properly acts as a type guard.
• objectKeys - A strongly-typed version of Object.keys().
• objectEntries - A strongly-typed version of Object.entries().
• objectFromEntries - A strongly-typed version of Object.fromEntries().
• objectHasOwn - A strongly-typed version of Object.hasOwn().
• isFinite - A strongly-typed version of Number.isFinite().
• isInteger - A strongly-typed version of Number.isInteger().
• isSafeInteger - A strongly-typed version of Number.isSafeInteger().

The type-fest package contains only types, meaning they are only used at compile-time and nothing is ever compiled into actual JavaScript code. This package contains functions that are compiled into JavaScript code and used at runtime.

• type-fest - A collection of essential TypeScript types
• is - Type guards for any situation