@polkadot/util/compact/addLength.js

A collection of useful utilities for @polkadot

import { u8aConcatStrict } from '../u8a/index.js';
import { compactToU8a } from './toU8a.js';
/**
 * @name compactAddLength
 * @description Adds a length prefix to the input value
 * @example
 * <BR>
 *
 * ```javascript
 * import { compactAddLength } from '@polkadot/util';
 *
 * console.log(compactAddLength(new Uint8Array([0xde, 0xad, 0xbe, 0xef]))); // Uint8Array([4 << 2, 0xde, 0xad, 0xbe, 0xef])
 * ```
 */
export function compactAddLength(input) {
    return u8aConcatStrict([
        compactToU8a(input.length),
        input
    ]);
}