Simultaneously Fetch URLs

Simultaneously fetch urls using Axios.

Usage

This module export doFetch function with the following signatures:

/**
 * @param {array<string|object>} queues The queues
 * @param {completeCallback} callback Queue completion callback
 */
async function doFetch(queues, callback) {
}

/**
 * @param {array<string|object>} queues The queues
 * @param {object} options The options
 * @param {number} options.worker Maximum number of simultaneous workers
 * @param {boolean} options.checkResult Fire callback only when request is successful or not
 * @param {Function} options.debug Debugger function
 * @param {completeCallback} callback Queue completion callback
 */
async function doFetch(queues, options, callback) {
}

The queues parameter can be a simple string array as of ['url', 'url', ...] or a complex object. For complex objects, the following property is recognized:

• url, the url to fetch.

• method, the method to use, either get or post is supported. If none specified it will be assumed as get.

• params, parameters which can includes request headers, URL parameters params, or anything else of Axios Request Config.

The callback will be called once each queue completed. The callback function signature is described as:

/**
 * @param {string|object} queue Fetched queue which is complete
 * @param {string|object} res Response content returned by axios
 * @param {object} headers Response headers returned by axios
 */
function callback(queue, res, headers) {
}

An additional configuration can be used to adjust doFetch behavior globally:

• The number of simultaneous workers by default set to 25 workers. To change the number of workers, call doFetch.setMaxWoker() with desired value, e.g. doFetch.setMaxWoker(10).

• The callback by default will not be fired if the response is empty. To force to always to fire the callback regardless of the response, set with doFetch.setCheckResult(false)

• To enable debugging, set the debugger function such as console.log using doFetch.setDebugger(console.log).

Examples

Fetch some urls

const doFetch = require('@ntlab/sfetch');

(async function run() {
    await doFetch([
        'https://example.com/foo',
        'https://example.com/bar'
    ], function(url, res, headers) {
        if (res) {
            // do something here
        }
    });
})();

Fetch some urls for further processing

const doFetch = require('@ntlab/sfetch');

(async function run() {
    const headers: {
        'User-Agent': 'My-User-Agent/1.0'
    }
    await doFetch([
        {
            for: 'foo',
            url: 'https://example.com/foo',
            method: 'get',
            params: {
                headers,
                params: { data: 'foo' }
            }
        },
        {
            for: 'bar',
            url: 'https://example.com/bar',
            method: 'post',
            params: {
                headers,
                params: { data: 'bar' },
                data: { bar: 'baz' }
            }
        }
    ], function(queue, res, headers) {
        if (queue.for === 'foo') {
            // do something for foo
        }
        if (queue.for === 'bar') {
            // do something for bar
        }
    });
})();

Queue more urls

const doFetch = require('@ntlab/sfetch');

(async function run() {
    const queues = ['https://example.com/foo']; 
    await doFetch(queues, function(url, res) {
        // queue returned urls from JSON response
        if (res && res.urls) {
            queues.push(...res.urls);
        }
    });
})();