dioxus/packages/web/NOTES.md

// ## RequestAnimationFrame and RequestIdleCallback // ------------------------------------------------ // React implements "jank free rendering" by deliberately not blocking the browser's main thread. For large diffs, long // running work, and integration with things like React-Three-Fiber, it's extremely important to avoid blocking the // main thread. // // React solves this problem by breaking up the rendering process into a "diff" phase and a "render" phase. In Dioxus, // the diff phase is non-blocking, using "work_with_deadline" to allow the browser to process other events. When the diff phase // is finally complete, the VirtualDOM will return a set of "Mutations" for this crate to apply. // // Here, we schedule the "diff" phase during the browser's idle period, achieved by calling RequestIdleCallback and then // setting a timeout from the that completes when the idleperiod is over. Then, we call requestAnimationFrame // // From Google's guide on rAF and rIC: // ----------------------------------- // // If the callback is fired at the end of the frame, it will be scheduled to go after the current frame has been committed, // which means that style changes will have been applied, and, importantly, layout calculated. If we make DOM changes inside // of the idle callback, those layout calculations will be invalidated. If there are any kind of layout reads in the next // frame, e.g. getBoundingClientRect, clientWidth, etc, the browser will have to perform a Forced Synchronous Layout, // which is a potential performance bottleneck. // // Another reason not trigger DOM changes in the idle callback is that the time impact of changing the DOM is unpredictable, // and as such we could easily go past the deadline the browser provided. // // The best practice is to only make DOM changes inside of a requestAnimationFrame callback, since it is scheduled by the // browser with that type of work in mind. That means that our code will need to use a document fragment, which can then // be appended in the next requestAnimationFrame callback. If you are using a VDOM library, you would use requestIdleCallback // to make changes, but you would apply the DOM patches in the next requestAnimationFrame callback, not the idle callback. // // Essentially: // ------------ // - Do the VDOM work during the idlecallback // - Do DOM work in the next requestAnimationFrame callback