Chrome 40 Beta: Powerful Offline and Lightspeed Loading with Service Workers
Thursday, December 4, 2014
The newest Chrome Beta channel release includes several new developer features to help you make richer, more compelling web content and apps, especially for mobile devices. Unless otherwise noted, changes described below apply to Chrome for Android, Windows, Mac, Linux, and Chrome OS.
Service Workers
This release adds service workers, a powerful new API that allows developers to make sites work offline by intercepting network requests to deliver programmatic or cached responses. Besides enabling a rich offline experience, developers can also use the API to achieve dramatic performance improvements by caching UI and other common resources between page loads.
Unlike other web technologies, the lifetime of a service worker is independent of the page that installed it. This lays the foundation for a new class of web applications with rich background capabilities. For example, future APIs like Push and Background Sync could do their work even after the page is closed, provided the user has given permission.
This release includes two new APIs for use only within service workers. The Fetch API allows service workers to make network requests—including cross-origin—and return the responses to pages they control. The Cache API can save fetched responses and then return them directly the next time the same resource is requested, bypassing the latency-prone network and the eviction-prone HTTP cache.
These APIs are still under active development and we are committed to keeping our implementation in sync with the specifications as they evolve. This release supports a subset of the Cache API, but developers can use a polyfill for full compatibility. If you’re interested in more in-depth information, check out HTML5 Rocks or our collection of useful service worker “recipes.”
Other updates in this release
Posted by Dominic Cooney and Joshua Bell, Software Engineers at your service
Service Workers
This release adds service workers, a powerful new API that allows developers to make sites work offline by intercepting network requests to deliver programmatic or cached responses. Besides enabling a rich offline experience, developers can also use the API to achieve dramatic performance improvements by caching UI and other common resources between page loads.
A before and after comparison of a repeat visitor loading a site that uses Service Workers.
Unlike other web technologies, the lifetime of a service worker is independent of the page that installed it. This lays the foundation for a new class of web applications with rich background capabilities. For example, future APIs like Push and Background Sync could do their work even after the page is closed, provided the user has given permission.
This release includes two new APIs for use only within service workers. The Fetch API allows service workers to make network requests—including cross-origin—and return the responses to pages they control. The Cache API can save fetched responses and then return them directly the next time the same resource is requested, bypassing the latency-prone network and the eviction-prone HTTP cache.
These APIs are still under active development and we are committed to keeping our implementation in sync with the specifications as they evolve. This release supports a subset of the Cache API, but developers can use a polyfill for full compatibility. If you’re interested in more in-depth information, check out HTML5 Rocks or our collection of useful service worker “recipes.”
Other updates in this release
- This release brings support for the new directives introduced in Content Security Policy (CSP) Level 2.
- The new reportValidity method causes Chrome to draw the user’s attention to form fields with validation errors, saving developers from needing to implement this feature manually in JavaScript.
- Chrome now supports the minlength attribute, a validation feature that allows developers to declare a lower bound on the number of characters a user can input.
- Thanks to a collaboration with Intel's Open Source Technology Center, Chrome on Mac now uses HarfBuzz for text shaping which improves performance and rendering of non-Latin text, brings new optimizations, and unifies the font system across all platforms.
- Developers can use the theme-color meta tag to customize their toolbar color in the app switcher on Android Lollipop.
Posted by Dominic Cooney and Joshua Bell, Software Engineers at your service