API Reference

getOrThrow

Get a value from an object or array, throwing an error if the key or index does not exist or if the resulting value is undefined.

Signatures

Array Access

function getOrThrow<T>(array: T[], index: number, errorMessage?: string): T;

Object Access

function getOrThrow<T extends object, K extends keyof T>(
  object: T,
  key: K,
  errorMessage?: string,
): NonNullable<T[K]>;

Parameters

Parameter	Type	Description
array / object	T[] | T	The array or object to access.
index / key	number | K	The index (for arrays) or key (for objects) to access.
errorMessage	string	Optional custom error message.

Returns

The value at the given key or index, guaranteed to be defined. For objects, the return type is NonNullable<T[K]>.

Throws

• If the index is out of bounds: "Index {n} is out of bounds."
• If the key does not exist: 'Key "{key}" does not exist in the object.'
• If the value is undefined: "Value at index {n} is undefined." or 'Value at key "{key}" is undefined.'

When a custom errorMessage is provided, it is used instead of the default messages.

Behavior

• Negative indexing: Negative indices count from the end of the array. got(arr, -1) returns the last element.
• Null values: null is treated as a valid value and does not trigger an error. Only undefined causes a throw.

got

An alias for getOrThrow. Both functions are identical — use whichever you prefer.

import { got } from "get-or-throw";
// is equivalent to
import { getOrThrow } from "get-or-throw";