问级联jQuery.Deferred

EN

My.prototype.init=function() {
    var $dfd = $.Deferred();

    this.initSomethingElse() // returns Deferred
        .done(function() {
            $dfd.resolve();
        })
        .fail(function() {
            $dfd.reject();
        });

    return $dfd;
}

My.prototype.init=function() {
    var $dfd = $.Deferred();

    this.initSomethingElse() // returns $.Deferred(addLinkMethodFce)
        .link($dfd);

    return $dfd;
}

/**
 * Adds some syntax sugar methods to Deferred object.
 *
 *   Deferred.link(dfd, ...) - if this object resolves/rejects/progresses it will resolve/reject/progress linked object as well
 *   Deferred.linkResolve(dfd, ...) - if this object resolves it will resolve linked object as well
 *   Deferred.linkReject(dfd, ...) - if this object rejects it will reject linked object as well
 *   Deferred.linkProgress(dfd, ...) - if this object progresss it will progress linked object as well
 *
 * Methods can be appended to Deferred object by two ways:
 *
 * $dfd = edfd($.Deferred());
 * $dfd = $.Deferred(edfd);
 *
 * @access public
 * @return {Deferred}
 */
function edfd($dfd) {

    /**
     * Helper used by this.link(), this.linkReject(), this.linkProgress(), this.linkResolve()
     *
     * @access private
     * @param {Boolean} accept link this Deferred's accept call to target's accept
     * @param {Boolean} reject link this Deferred's reject call to target's reject
     * @param {Boolean} progress link this Deferred's progress call to target's progress
     * @param {Object} targets array of Deferreds or array of arrays of Deferreds
     * @return {Deferred} this (called in $dfd context)
     */
    function linker(accept, reject, progress, targets) {
        targets = dna.core.getOpts(targets, [['dfdList', 'object'], 'recursive']);

        for (var i = 0; i < targets.dfdList.length; i++) {
            var $link = targets.dfdList[i];
            $dfd.then(
                accept && function() {$link.resolve.apply($link, arguments);},
                reject && function() {$link.reject.apply($link, arguments);},
                progress && function() {$link.progress.apply($link, arguments);}
            );
        }

        return this;
    }

    /**
     * If link this Deferred's rejection/resolution/progress to all linked Deferreds.
     *
     * @access public
     * @param {...Deferred} dfd jQuery Deferred objects or arrays of Deferred objects.
     * @return {Deferred} this object
     */
    $dfd.link = function() {
        return linker(true, true, true, arguments);
    };

    /**
     * If this Deferred is resolved then resolve also linked Deferreds.
     *
     * @access public
     * @param {...Deferred} dfd jQuery Deferred objects or arrays of Deferred objects.
     * @return {Deferred} this object
     */
    $dfd.linkResolve = function() {
        return linker(true, false, false, arguments);
    };

    /**
     * If this Deferred gets rejected then reject also linked Deferreds.
     *
     * @access public
     * @param {...Deferred} dfd jQuery Deferred objects or arrays of Deferred objects.
     * @return {Deferred} this object
     */
    $dfd.linkReject = function() {
        return linker(false, true, false, arguments);
    };

    /**
     * If this Deferred progresses then progress also linked Deferreds.
     *
     * @access public
     * @param {...Deferred} dfd jQuery Deferred objects or arrays of Deferred objects.
     * @return {Deferred} this object
     */
    $dfd.linkProgress = function() {
        return linker(false, false, true, arguments);
    };

    return $dfd;
}

/**
 * Public interface as required for payment processors.
 *
 * @access public
 * @param {Object} payData
 * @return {Deferred} resolved/rejected based on payment result.
 */
Braintree.prototype.process = function(payData) {
    this.cleanUp();
    this.payData = payData;
    this.createLayer();
    this.initBraintree(payData.clientToken)
        .linkReject(this.$dfd);

    return this.$dfd;
};