可靠地检测脚本是否在Web worker中执行 [英] Reliably detect if the script is executing in a web worker

问题描述

我目前正在用JavaScript编写一个小库来帮助我委托一个网络工作者进行一些繁重的计算。

I am currently writing a little library in JavaScript to help me delegate to a web-worker some heavy computation .

出于某些原因（主要是因为调试能力）在UI线程中然后在worker中运行相同的代码）我想检测脚本当前是在worker还是在UI线程中运行。

For some reasons (mainly for the ability to debug in the UI thread and then run the same code in a worker) I'd like to detect if the script is currently running in a worker or in the UI thread.

我不是一个经验丰富的JavaScript开发人员，我想确保以下函数能够可靠地检测我是否在工作中：

I'm not a seasoned JavaScript developper and I would like to ensure that the following function will reliably detect if I'm in a worker or not :

function testenv() {
    try{
        if (importScripts) {
            postMessage("I think I'm in a worker actually.");
        }
    } catch (e) {
        if (e instanceof ReferenceError) {
            console.log("I'm the UI thread.");
        } else {
            throw e;
        }
    }
}

那么，是吗？ / p>

So, does it ?

推荐答案

如上所述，答案在，它说要检查窗口上是否存在文档对象。我想对您的代码进行修改以避免执行try / catch块，也可能在其他浏览器中减慢。

As noted there is an answer in another thread which says to check for the presence of a document object on the window. I wanted to however make a modification to your code to avoid doing a try/catch block which slows execution of JS in Chrome and likely in other browsers as well.

编辑：之前我假设有一个错误全局范围内的窗口对象。我通常添加

I made an error previously in assuming there was a window object in the global scope. I usually add

//This is likely SharedWorkerContext or DedicatedWorkerContext
window=this;

到我的工作者加载器脚本的顶部，这允许所有使用窗口特征检测的函数不会爆炸。然后你可以使用下面的函数。

to the top of my worker loader script this allows all functions that use window feature detection to not blow up. Then you may use the function below.

function testEnv() {
  if (window.document === undefined) {
    postMessage("I'm fairly confident I'm a webworker");
  } else {
    console.log("I'm fairly confident I'm in the renderer thread");
  }
}

或者没有窗口分配，只要它在顶部等级范围。

Alternatively without the window assignment as long as its at top level scope.

var self = this;
function() {
  if(self.document === undefined) {
    postMessage("I'm fairly confident I'm a webworker");
  } else {
    console.log("I'm fairly confident I'm in the renderer thread");
  }
}

这篇关于可靠地检测脚本是否在Web worker中执行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！