检测页面是否将Angular 2+与JavaScript一起使用

Question

I am using Google Polymer on top of an Angular 2 app and I need a way in the Polymer JavaScript to determine if the page in running Angular 2 or not. I had read somewhere that if (window.ng) {} works and it has for me up until yesterday. Now, it works in localhost but has stopped working on my test and production servers. Now, window.ng is undefined.

When I debug the Polymer JavaScript and step through it slowely, I get the following console errors:

(WEB_PAGE context) Lazy require of app.binding did not set the binding field
(WEB_PAGE context) Lazy require of webstore.binding did not set the binding field
(WEB_PAGE context) Lazy require of runtime.binding did not set the binding field

Any help would be much appreciated!

Answer 1

Angular automatically adds an attribute ng-version to the root component's tag, so you can parse that attribute's value like this assuming the root component is the first child of body

const majorVersion = parseInt(document.body.children[0].getAttribute('ng-version').split('.')[0])
console.log(majorVersion >= 2);