useSubscription and useMutableSource1 tearing and deopt behavior.
The tree below represents a React application mounting. During mount, two components read from an external, mutable source. The first one (List) reads version 1 of that data and the second one (Item) reads version 2.
N/A.
Note:
When this guide is more complete, the plan is to move it into Prepack documentation.
For now I put it out as a gist to gather initial feedback.
If you're building JavaScript apps, you might already be familiar with some tools that compile JavaScript code to equivalent JavaScript code:
Javascript files from the examples folder (such as OrbitControls) are not CommonJS or ES Modules, but they can still be used in Webpack bundles:
In package.json:
"dependencies": {
"three": "0.84.0",
"webpack": "2.4.1"
}
| import os, asyncnet, asyncdispatch | |
| proc callback1(): Future[int] = | |
| var retFuture = newFuture[int]("callback1") | |
| echo "Callback1: Waiting" | |
| sleep(3000) | |
| retFuture.complete(10) | |
| return retFuture |
Let's say we want to computer the area of some Shape types like Square and Circle
We may have some function called sum-areas that takes a list of Shape , calls area on each of them, and sums them up. We don't have access to the original source, but want the ability to add new shapes.
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>Test App</title> | |
| </head> | |
| <style> | |
| html, body { | |
| height: 100%; |
I really liked @tjvantoll article Handling Failed HTTP Responses With fetch(). The one thing I found annoying with it, though, is that response.statusText always returns the generic error message associated with the error code. Most APIs, however, will generally return some kind of useful, more human friendly message in the body.
Here's a modification that will capture this message. The key is that rather than throwing an error, you just throw the response and then process it in the catch block to extract the message in the body:
fetch("/api/foo")
.then( response => {
if (!response.ok) { throw response }
return response.json() //we only get here if there is no error
})
This very simple and minimal tutorial documents in a few easy steps how to play with WebAssembly (WASM) and get first results within minutes.
While the code below is mostly useless, it will show, how to call the alert function from within a WASM file and thus demonstrate how to import and export DOM objects.
Of course, this exercise has no real use. It is just meant to show, that getting started with WASM isn't hard. And there is no need for a complex build-chain, tons of tools or a dedicated VMs. Just use a browser, one online tool and that's it.
All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.
Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.
elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent