@feathersjs/hooks/esm/compose.js

Async middleware for JavaScript and TypeScript

export function compose(middleware) {
    if (!Array.isArray(middleware)) {
        throw new TypeError('Middleware stack must be an array!');
    }
    for (const fn of middleware) {
        if (typeof fn !== 'function') {
            throw new TypeError('Middleware must be composed of functions!');
        }
    }
    return function (context, next) {
        // last called middleware #
        let index = -1;
        return dispatch.call(this, 0);
        function dispatch(i) {
            if (i <= index) {
                return Promise.reject(new Error('next() called multiple times'));
            }
            index = i;
            let fn = middleware[i];
            if (i === middleware.length) {
                fn = next;
            }
            if (!fn) {
                return Promise.resolve();
            }
            try {
                return Promise.resolve(fn.call(this, context, dispatch.bind(this, i + 1)));
            }
            catch (err) {
                return Promise.reject(err);
            }
        }
    };
}