certificate_prefetch.js

var that = this;

// Create a class that "inherits" from CoreCourseActivityPrefetchHandlerBase.
function AddonModCertificateModulePrefetchHandler() {
    that.CoreCourseActivityPrefetchHandlerBase.call(this, that.TranslateService, that.CoreAppProvider, that.CoreUtilsProvider,
            that.CoreCourseProvider, that.CoreFilepoolProvider, that.CoreSitesProvider, that.CoreDomUtilsProvider);

    this.name = "AddonModCertificateModulePrefetchHandler";
    this.modName = "certificate";
    this.component = "AddonModCertificate";
    this.updatesNames = /^configuration$|^.*files$|^entries$/;
}

AddonModCertificateModulePrefetchHandler.prototype = Object.create(this.CoreCourseActivityPrefetchHandlerBase.prototype);
AddonModCertificateModulePrefetchHandler.prototype.constructor = AddonModCertificateModulePrefetchHandler;

// Override the prefetch call.
AddonModCertificateModulePrefetchHandler.prototype.prefetch = function(module, courseId, single, dirPath) {
    return this.prefetchPackage(module, courseId, single, prefetchCertificate);
};

function prefetchCertificate(module, courseId, single, siteId) {
    // Perform all the WS calls.
    // You can access most of the app providers using that.ClassName. E.g. that.CoreWSProvider.call().
}

// Register the handler.
this.CoreCourseModulePrefetchDelegate.registerHandler(new AddonModCertificateModulePrefetchHandler());