@cosmjs/utils

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");

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
}

Function	Parameters	Returns
`sleep`	`ms: number`	`Promise<void>`

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

await sleep(1000); // wait 1 second

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).