webglcontextcreationerror事件：是否同步触发？ [英] webglcontextcreationerror event: is it triggered synchronously?

问题描述

同步或异步触发 webglcontextcreationerror事件吗？例如

  canvas.addEventListener（webglcontextcreationerror，function（）{
 console.log（Error ）; 
}）; 
 var context = canvas.getContext（webgl）; 
 console.log（创建后）; 
  

在错误输出的情况下

创建后
错误
  

或

 错误
创建后
  

？

我不确定如何强制这个事件自己找出答案。 b 注意：这不是每个规范的答案，而是仅来自单个UA测试，因此可能是错误的，或者至少只适用于这个UA，也就是Chrome。

---

在chrome中，为了强制错误事件，您可以首先请求一个2dContext然后一个webgl。

通过这种方式，我们可以看到这个UA将事件视为同步事件。

_{我刚刚了解这些事情 - 现在...}

{snippet.log（Error）;}）; canvas.getContext（'2d'）canvas.getContext（webgl）; snippet.log（创建后）;

<！ - 提供`snippet`对象，请参阅http://meta.stackexchange.com / a / 242144/134069 - >< script src =http://tjcrowder.github.io/simple-snippets-console/snippet.js>< / script>

Is the webglcontextcreationerror event triggered synchronously or asynchronously? For example does

canvas.addEventListener("webglcontextcreationerror", function() {
  console.log("Error");
});
var context = canvas.getContext("webgl");
console.log("After creation");

in the case of error output

"After creation"
"Error"

or

"Error"
"After creation"

?

I am unsure how to force this event to find out the answer myself.

解决方案

NB : This is not a per spec answer, but only from a single UA test, so it may be wrong, or at least true only to this UA, a.k.a Chrome.

---

In chrome, to force the error event, you can first request a 2dContext then a webgl one.

This way we can see that this UA does treat the event as an synchronous one.
_{I just learn about these right-now...}

var canvas = document.createElement('canvas')

canvas.addEventListener("webglcontextcreationerror", function() {
  snippet.log("Error");
});

canvas.getContext('2d')
canvas.getContext("webgl");

snippet.log("After creation");

<!-- Provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

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