@polkadot/util/u8a/cmp.js

A collection of useful utilities for @polkadot

import { u8aToU8a } from './toU8a.js';
/**
 * @name u8aCmp
 * @summary Compares two Uint8Arrays for sorting.
 * @description
 * For `UInt8Array` (or hex string) input values returning -1, 0 or +1
 * @example
 * <BR>
 *
 * ```javascript
 * import { u8aCmp } from '@polkadot/util';
 *
 * u8aCmp(new Uint8Array([0x67, 0x65]), new Uint8Array([0x68, 0x65])); // -1
 * u8aCmp(new Uint8Array([0x68, 0x65]), new Uint8Array([0x68, 0x65])); // 0
 * u8aCmp(new Uint8Array([0x69, 0x65]), new Uint8Array([0x68, 0x65])); // +1
 * ```
 */
export function u8aCmp(a, b) {
    const u8aa = u8aToU8a(a);
    const u8ab = u8aToU8a(b);
    let i = 0;
    while (true) {
        const overA = i >= u8aa.length;
        const overB = i >= u8ab.length;
        if (overA && overB) {
            // both ends reached
            return 0;
        }
        else if (overA) {
            // a has no more data, b has data
            return -1;
        }
        else if (overB) {
            // b has no more data, a has data
            return 1;
        }
        else if (u8aa[i] !== u8ab[i]) {
            // the number in this index doesn't match
            // (we don't use u8aa[i] - u8ab[i] since that doesn't match with localeCompare)
            return u8aa[i] > u8ab[i]
                ? 1
                : -1;
        }
        i++;
    }
}