Layout Jank API Example

(2019-03-08) Now this feature is enabled under the origin trial. Please try it out on +M73.

What is the Layout Jank API?

Layout Jank API is the part of web performance APIs that allows to monitor the degree to which DOM elements have changed their on-screen position ("layout jank") during the user's session.

Developer can observe "layout jank" by adding following example.

        
        new PerformanceObserver(list => {
          list.getEntries().forEach(entry => {
            console.log(entry.fraction);
          });
        }).observe({
          entryTypes: ['layoutJank']
        });

Change window size or viewport and see fraction score go up/down!

Platform Status
Documentation

Last layout stability metric fraction score:
Total score since navigation happened: