Apple releases second Safari Technology Preview update with rendering and Web Inspector improvements

Apple today released the second update to its Safari Technology Preview browser intended for developers. The browser doesn’t look very different from the two earlier versions of this browser, nor does it function in a way that’s very different from regular Safari. But this release brings many more updates to the code under the hood.

With respect to JavaScript, Apple has done more to bring the preview browser up to spec with ECMAScript 6. For instance, there is now support for the Symbol.isConcatSpreadable and RegExp.prototype[@@split] functions, and the browser has “improved parsing of ES6 arrow functions,” Apple said in today’s release notes.

Today’s release comes with many additions when it comes to rendering. For example, Apple said it has reduced “the time to display for some pages — allowing a short page header to render immediately before other content populates later.” And there are bug fixes — for example, there is no longer compositing for WebGL canvases once the size has been adjusted.

The Web Inspector tool is also getting more powerful with today’s release. Apple said it has “[i]mproved performance dramatically in the Timelines tab when recording pages with a lot of rapid activity and for long recordings,” for one thing. And developers can now run full-text searches on Web Workers and XMLHttpRequests (XHRs), too. Plus, the browser will remember how much you zoom in with the Web Inspector and use that level across each session. (See the full release notes for information on the rest of the changes.)

This marks the second update to the original Safari Technology Preview in one month. If you want to try out the Safari Technology Preview, you’ll need OS X 10.11.4 or a newer version of OS X. You can download the browser here.