shelving/react/useInstance.js

Toolkit for using data in JavaScript.

import { useRef } from "react";
import { isArrayEqual } from "../util/equal.js";
/**
 * Use a memoised class instance.
 * - Creates a new instance of `Constructor` using `args`
 * - Returns same instance for as long as `args` is equal to previous `args`.
 */
export function useInstance(Constructor, ...args) {
    const _internals = (useRef(undefined).current ??= {
        instance: new Constructor(...args),
        args,
    });
    // Update `_internals` if `args` changes.
    if (!isArrayEqual(args, _internals.args)) {
        _internals.instance = new Constructor(...args);
        _internals.args = args;
    }
    return _internals.instance;
}