broker-factory/build/es2019/factories/create-broker.js

A little factory function to create a broker for a JSON-RPC based Web Worker.

export const createBrokerFactory = (createOrGetOngoingRequests, extendBrokerImplementation, generateUniqueNumber, isMessagePort) => (brokerImplementation) => {
    const fullBrokerImplementation = extendBrokerImplementation(brokerImplementation);
    return (sender) => {
        const ongoingRequests = createOrGetOngoingRequests(sender);
        sender.addEventListener('message', (({ data: message }) => {
            const { id } = message;
            if (id !== null && ongoingRequests.has(id)) {
                const { reject, resolve } = ongoingRequests.get(id);
                ongoingRequests.delete(id);
                if (message.error === undefined) {
                    resolve(message.result);
                }
                else {
                    reject(new Error(message.error.message));
                }
            }
        }));
        if (isMessagePort(sender)) {
            sender.start();
        }
        const call = (method, params = null, transferables = []) => {
            return new Promise((resolve, reject) => {
                const id = generateUniqueNumber(ongoingRequests);
                ongoingRequests.set(id, { reject, resolve });
                if (params === null) {
                    sender.postMessage({ id, method }, transferables);
                }
                else {
                    sender.postMessage({ id, method, params }, transferables);
                }
            });
        };
        const notify = (method, params, transferables = []) => {
            sender.postMessage({ id: null, method, params }, transferables);
        };
        let functions = {};
        for (const [key, handler] of Object.entries(fullBrokerImplementation)) {
            functions = { ...functions, [key]: handler({ call, notify }) };
        }
        return { ...functions };
    };
};
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