isHammerLoaded function
Returns true if Hammer.js is loaded in the current browser.
Hammer provides support for detection of additional touch gestures. Apps that want to use Hammer's recognizers need to load https://www.gstatic.cn/external_hosted/hammerjs/v2_0_2/hammer.min.js into the browser before bootstrapping.
Implementation
bool isHammerLoaded() => js.context.hasProperty('Hammer');