The UI is nearly as responsive as their improved example.
I'm not a React expert, but I do know that browsers defer timeouts until they have time to process them. This can be used to take heavy-hitting functions out of events that block UI interactions. It can also be used for self-throttling recursive IIFEs.
If you delay the artificial slowness that I added in the Text component after the rendering, it sure will be faster. The point is to simulate an expensive component tree with this.
Here is by the way a version with all artificial slowness removed: https://codesandbox.io/s/9859x0wm9p You can see that this example does not need any optimizations out of the box. This is why I added the slowness to simulate a more complex app.
The important part btw is that in Concurrent Mode we can interrupt a render in the middle if user does an interaction, and handle that interaction first. Without blocking the thread.
This is something setTimeout is incapable of helping with. Because even if you delay the work, at some point it’s still gonna block.
In either case this example is very simplified and doesn’t illustrate the subtle difference as much. We’ll prepare our own examples when the features are stable.
No, that's not possible in JavaScript. The important part is that React components are lazily evaluated[1] and are not rendered as a stack. So React can render a few components and then pause for higher priority work.
As a user of the framework, you don't need to care about this though. So your mental model can be that of an interruptable function.
I think to interrupt a render means interrupt the process of reconciliation. you don't have to response the user input until the difference of whole React element has been found.
https://overreacted.io/react-as-a-ui-runtime/#consistency
There's a lot of nuance involved here. Moving some behavior outside the current tick may speed certain things up. Keeping multiple React updates in the same tick may _also_ speed other things up. It depends on what work is being done in these additional callbacks, and where/when they're being executed.
In this specific case: `this.props.onChange()` calls the parent component's `setState()`. That should ideally be kept in the same tick as `this.setState()`, so they can be batched.
`sendAnalyticsPing()` does _not_ cause a React update. That should indeed be moved out to a separate tick, so that it doesn't slow down this update.
https://codesandbox.io/s/07293kpnn
The UI is nearly as responsive as their improved example.
I'm not a React expert, but I do know that browsers defer timeouts until they have time to process them. This can be used to take heavy-hitting functions out of events that block UI interactions. It can also be used for self-throttling recursive IIFEs.