x-http-client/lib/http/addEventListeners.js

An http client to make it easier to send requests (including JSONP requests) to the server.

var isFunction = require('x-common-utils/isFunction');
var HttpResponse = require('../class/HttpResponse');
var addTimeoutListener = require('./addTimeoutListener');
var fireCallbacks = require('../shared/fireCallbacks');
var noop = require('../shared/noop');
var constants = require('../shared/constants');
var ERR_ABORTED   = constants.ERR_ABORTED;
var ERR_CANCELLED = constants.ERR_CANCELLED;
var ERR_NETWORK   = constants.ERR_NETWORK;
var ERR_RESPONSE  = constants.ERR_RESPONSE;
var ERR_TIMEOUT   = constants.ERR_TIMEOUT;

/**
 * Add event listeners to the http request. This function will overwite the `cancel` method on the given `HttpReqest`
 * instance.
 *
 * @param {HttpRequest} request The http request to add event listeners.
 */
function addEventListeners(request) {
    var xhr = request.xhr;
    var options = request.options;
    var requestType = request.requestType;
    var response = new HttpResponse(request);
    var isResponseOk = options.isResponseOk;
    var clearTimeoutEvent = null;
    var timeout = parseInt(options.timeout || 0, 10);

    /**
     * Cancel the request.
     */
    var cancel = function () {
        clearEvents();
        if (xhr.abort) {
            try {
                xhr.abort();
            } catch (e) {
                // empty
            }
        }
        finish(ERR_CANCELLED);
    };

    /**
     * The function to clear events.
     */
    var clearEvents = function () {
        // Set clearEvents to the noop function.
        clearEvents = noop;

        xhr.onabort = null;
        xhr.onerror = null;
        xhr.onreadystatechange = null;
        xhr.ontimeout = null;

        if (clearTimeoutEvent) {
            clearTimeoutEvent();
            clearTimeoutEvent = null;
        }
    };

    /**
     * The function finish the request.
     *
     * @param {string} code The error code on error. If no error occured, the code is `null`.
     */
    var finish = function (code) {
        // Set finish to the noop function.
        finish = noop;

        // Set cancel to the noop function.
        cancel = noop;

        // Mark this request as finished.
        request.finished = true;

        // Clear events.
        clearEvents();

        // Fire callbacks.
        fireCallbacks(code, response);
    };

    xhr.onabort = function () {
        finish(ERR_ABORTED);
    };

    xhr.onerror = function () {
        finish(ERR_NETWORK);
    };

    xhr.onreadystatechange = function () {
        if (+xhr.readyState === 4) {
            if (isFunction(isResponseOk)) {
                if (isResponseOk(requestType, response)) {
                    finish(null);
                } else {
                    finish(ERR_RESPONSE);
                }
            } else {
                finish(null);
            }
        }
    };

    /**
     * Cancel the request.
     */
    request.cancel = function () {
        cancel();
    };

    // Add timeout listener
    if (!isNaN(timeout) && timeout > 0) {
        clearTimeoutEvent = addTimeoutListener(xhr, timeout, function () {
            clearEvents();
            if (xhr.abort) {
                try {
                    xhr.abort();
                } catch (e) {
                    // empty
                }
            }
            finish(ERR_TIMEOUT);
        });
    }
}

module.exports = addEventListeners;