@cosmjs/utils

Assertion and utility helpers

Lightweight utility functions for assertions, type guards, and async helpers used throughout CosmJS.

npm install @cosmjs/utils

Assertions

Function	Parameters	Returns
assert	condition: any, msg?: string	asserts condition (throws if falsy)
assertDefined	value: T | undefined, msg?: string	asserts value is T (throws if undefined)
assertDefinedAndNotNull	value: T | undefined | null, msg?: string	asserts value is T (throws if null/undefined)

These helpers use TypeScript assertion signatures, so the compiler narrows the type of the argument in the enclosing scope after a successful call.

import { assert, assertDefined } from "@cosmjs/utils";

assert(amount > 0, "Amount must be positive");
assertDefined(account, "Account not found");

Type Guards

Function	Parameters	Returns
isDefined	value: T | undefined	value is T
isNonNullObject	data: unknown	data is object (also matches arrays)
isUint8Array	value: unknown	value is Uint8Array

import { isDefined, isNonNullObject } from "@cosmjs/utils";

if (isDefined(optional)) {
  optional.property; // TypeScript knows it's defined
}

Async Helpers

Function	Parameters	Returns
sleep	ms: number	Promise<void>

import { sleep } from "@cosmjs/utils";

await sleep(1000); // wait 1 second

Array Utilities

Function	Parameters	Returns
arrayContentEquals<T>	a: ArrayLike<T>, b: ArrayLike<T> where T extends string | number | boolean	boolean
arrayContentStartsWith<T>	a: ArrayLike<T>, b: ArrayLike<T> where T extends string | number | boolean	boolean

Elements are compared with strict equality, so these helpers only support arrays of primitives (string/number/boolean).