ketting/dist/http/fetcher.js

Opinionated HATEOAS / Rest client.

import problemFactory from './error.js';
import packageJson from 'ketting/package.json' with { type: 'json' };
/**
 * The fetcher object is responsible for calling fetch()
 *
 * This is wrapped in an object because we want to support
 * 'fetch middlewares'. These middlewares are similar to server-side
 * middlewares and can intercept requests and alter requests/responses.
 */
export class Fetcher {
    middlewares = [];
    advertiseKetting = true;
    /**
     * A wrapper for MDN fetch()
     *
     * This wrapper supports 'fetch middlewares'. It will call them
     * in sequence.
     */
    fetch(resource, init) {
        const request = new Request(resource, init);
        const origin = new URL(request.url).origin;
        const mws = this.getMiddlewaresByOrigin(origin);
        mws.push((innerRequest) => {
            if (!innerRequest.headers.has('User-Agent') && this.advertiseKetting) {
                // eslint-disable-next-line @typescript-eslint/no-require-imports
                innerRequest.headers.set('User-Agent', `Ketting/${packageJson.version}`);
            }
            return fetch(innerRequest);
        });
        return invokeMiddlewares(mws, request);
    }
    /**
     * Returns the list of middlewares that are applicable to
     * a specific origin
     */
    getMiddlewaresByOrigin(origin) {
        return this.middlewares.filter(([regex]) => {
            return regex.test(origin);
        }).map(([, middleware]) => {
            return middleware;
        });
    }
    /**
     * Add a middleware
     */
    use(mw, origin = '*') {
        const matchSplit = origin.split('*');
        const matchRegex = matchSplit.map(part => part.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')).join('(.*)');
        const regex = new RegExp('^' + matchRegex + '$');
        this.middlewares.push([regex, mw]);
    }
    /**
     * Does a HTTP request and throws an exception if the server emitted
     * a HTTP error.
     *
     * @see https://developer.mozilla.org/en-US/docs/Web/API/Request/Request
     */
    async fetchOrThrow(resource, init) {
        const response = await this.fetch(resource, init);
        if (response.ok) {
            return response;
        }
        else {
            throw await problemFactory(response);
        }
    }
}
export default Fetcher;
function invokeMiddlewares(mws, request) {
    return mws[0](request, (nextRequest) => {
        return invokeMiddlewares(mws.slice(1), nextRequest);
    });
}
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