I have started to load a few key resources and pages using the prefetch/prerender system.
Is there a way to ensure that the resources in question are actually being preloaded?
Google recommends using the Page Visibility API to test if a page is being prerendered. I'm not sure how well it works cross-browser (but what does in HTML5).
You can also use prerender-test.appspot.com to test that your site works correctly under prerendering. Further, from within Chrome, you can go to chrome://net-internals#prerender to see a list of attempted prerenders and whether they were used, and if they were not used, why they were canceled.
来源：https://stackoverflow.com/questions/7431366/how-to-test-prefetch-prerender