Question

如何使用字符串创建Web worker（通过POST请求提供）？

我能想到的一种方法，但我不确定如何实现它，是通过从服务器响应创建数据URI，并将其传递给Worker构造函数，但我听说有些浏览器不知道不允许这样，因为原产地政策相同。

MDN states the uncertainty about the origin policy around data URI's：

注意：作为Worker构造函数的参数传递的URI必须遵循同源策略。目前，浏览器供应商对数据URI是否来源不一致存在分歧; Gecko 10.0（Firefox 10.0 / Thunderbird 10.0）及更高版本确实允许数据URI作为工作人员的有效脚本。其他浏览器可能不同意。

这里还有帖子discussing it on the whatwg。

Answer 1

摘要


blob:适用于Chrome 8 +，Firefox 6 +，Safari 6.0 +，Opera 15 +

data:application/javascript适用于Opera 10.60 - 12

eval否则（IE 10 +）

URL.createObjectURL(<Blob blob>)可用于从字符串创建Web worker。可以使用BlobBuilder API ^已弃用或Blob constructor创建blob。

演示：http://jsfiddle.net/uqcFM/49/

// URL.createObjectURL
window.URL = window.URL || window.webkitURL;

// "Server response", used in all examples
var response = "self.onmessage=function(e){postMessage('Worker: '+e.data);}";

var blob;
try {
    blob = new Blob([response], {type: 'application/javascript'});
} catch (e) { // Backwards-compatibility
    window.BlobBuilder = window.BlobBuilder || window.WebKitBlobBuilder || window.MozBlobBuilder;
    blob = new BlobBuilder();
    blob.append(response);
    blob = blob.getBlob();
}
var worker = new Worker(URL.createObjectURL(blob));

// Test, used in all examples:
worker.onmessage = function(e) {
    alert('Response: ' + e.data);
};
worker.postMessage('Test');

兼容性

以下浏览器支持Web worker ^source：

Chrome 3
Firefox 3.5
IE 10
Opera 10.60
Safari 4

此方法的支持基于Blob API和URL.createObjectUrl方法的支持。 Blob compatibility：

Chrome 8+（WebKitBlobBuilder），20 +（Blob构造函数）
Firefox 6+（MozBlobBuilder），13 +（Blob构造函数）
Safari 6+（Blob构造函数）

IE10支持MSBlobBuilder和URL.createObjectURL。但是，尝试从blob: - URL创建Web Worker会引发SecurityError。

Opera 12不支持URL API。由于this hack in browser.js，有些用户可能会伪造URL个对象。

后备1：数据URI

Opera支持将数据URI作为Worker构造函数的参数。注意：不要忘记escape special characters（例如#和%）。

// response as defined in the first example
var worker = new Worker('data:application/javascript,' +
                        encodeURIComponent(response) );
// ... Test as defined in the first example

演示：http://jsfiddle.net/uqcFM/37/

后退2：Eval

eval可用作Safari（＆lt; 6）和IE 10的后备广告。

// Worker-helper.js
self.onmessage = function(e) {
    self.onmessage = null; // Clean-up
    eval(e.data);
};
// Usage:
var worker = new Worker('Worker-helper.js');
// `response` as defined in the first example
worker.postMessage(response);
// .. Test as defined in the first example

Answer 2

我同意当前接受的答案，但经常编辑和管理工作人员代码将会以字符串的形式出现。

所以我们可以选择使用下面的方法，我们可以将worker作为一个函数，然后转换为string-＆gt; blob：

// function to be your worker
function workerFunction() {
    var self = this;
    self.onmessage = function(e) {
        console.log('Received input: ', e.data); // message received from main thread
        self.postMessage("Response back to main thread");
    }
}


///////////////////////////////

var dataObj = '(' + workerFunction + ')();'; // here is the trick to convert the above fucntion to string
var blob = new Blob([dataObj.replace('"use strict";', '')]); // firefox adds "use strict"; to any function which might block worker execution so knock it off

var blobURL = (window.URL ? URL : webkitURL).createObjectURL(blob, {
    type: 'application/javascript; charset=utf-8'
});


var worker = new Worker(blobURL); // spawn new worker

worker.onmessage = function(e) {
    console.log('Worker said: ', e.data); // message received from worker
};
worker.postMessage("some input to worker"); // Send data to our worker.

这是在IE11 +和FF以及Chrome

中测试的

Answer 3

我已经用你的大多数想法做了一些方法并添加了我的一些想法。我的代码唯一需要的工作就是使用＆＃39;这个＆＃39;引用＆＃39; self＆＃39;范围。我非常确定这是非常可以改进的：

// Sample code
var code = function() {
    this.onmessage = function(e) {
        this.postMessage('Worker: '+e.data);
        this.postMessage('Worker2: '+e.data);
    };
};

// New thread worker code
FakeWorkerCode = function(code, worker) {
    code.call(this);
    this.worker = worker;
}
FakeWorkerCode.prototype.postMessage = function(e) {
    this.worker.onmessage({data: e});
}
// Main thread worker side
FakeWorker = function(code) {
    this.code = new FakeWorkerCode(code, this);
}
FakeWorker.prototype.postMessage = function(e) {
    this.code.onmessage({data: e});
}

// Utilities for generating workers
Utils = {
    stringifyFunction: function(func) {
        // Stringify the code
        return '(' + func + ').call(self);';
    },
    generateWorker: function(code) {
        // URL.createObjectURL
        windowURL = window.URL || window.webkitURL;   
        var blob, worker;
        var stringified = Utils.stringifyFunction(code);
        try {
            blob = new Blob([stringified], {type: 'application/javascript'});
        } catch (e) { // Backwards-compatibility
            window.BlobBuilder = window.BlobBuilder || window.WebKitBlobBuilder || window.MozBlobBuilder;
            blob = new BlobBuilder();
            blob.append(stringified);
            blob = blob.getBlob();
        }

        if ("Worker" in window) {
            worker = new Worker(windowURL.createObjectURL(blob));
        } else {
            worker = new FakeWorker(code);
        }
        return worker;
    }
};

// Generate worker
var worker = Utils.generateWorker(code);
// Test, used in all examples:
worker.onmessage = function(e) {
    alert('Response: ' + e.data);
};
function runWorker() {
    worker.postMessage('working fine');
}

演示：http://jsfiddle.net/8N6aR/

Answer 4

由于支持向后兼容性，因此可接受的答案有点复杂，因此我想发布相同的内容，但简化了。在您的（现代）浏览器控制台中尝试以下操作：

const code = "console.log('Hello from web worker!')"
const blob = new Blob([code], {type: 'application/javascript'})
const worker = new Worker(URL.createObjectURL(blob))
// See the output in your console.

Answer 5

很好的答案 - 当我们尝试创建具有后备功能的Web Workers时，我一直在研究类似的问题（即在主线程中运行工作程序脚本）。由于这个主题与主题有关，我想我会在这里提供我的解决方案：

    <script type="javascript/worker">
        //WORKER FUNCTIONS
        self.onmessage = function(event) {
            postMessage('Hello, ' + event.data.name + '!');
        }
    </script>

    <script type="text/javascript">

        function inlineWorker(parts, params, callback) {

            var URL = (window.URL || window.webkitURL);

            if (!URL && window.Worker) {

                var worker = new window.Worker(URL.createObjectURL(new Blob([parts], { "type" : "text/javascript" })));

                worker.onmessage = function(event) {
                  callback(event.data);
                };

                worker.postMessage(params);

            } else {

                var postMessage = function(result) {
                  callback(result);
                };

                var self = {}; //'self' in scope of inlineWorker. 
                eval(parts); //Converts self.onmessage function string to function on self via nearest scope (previous line) - please email chrisgwgreen.site@gmail.com if this could be tidier.
                self.onmessage({ 
                    data: params 
                });
            }
        }

        inlineWorker(
            document.querySelector('[type="javascript/worker"]').textContent, 
            {
                name: 'Chaps!!'
            },
            function(result) {
                document.body.innerHTML = result;
            }
        );

    </script>
</body>

Answer 6

根据您的使用情况，您可以使用类似

的内容

task.js 简化界面，让CPU密集型代码在所有核心（node.js和web）上运行

一个例子是

// turn blocking pure function into a worker task
const functionFromPostRequest = task.wrap('function (exampleArgument) {}');

// run task on a autoscaling worker pool
functionFromPostRequest('exampleArgumentValue').then(result => {
    // do something with result
});

Answer 7

扩展@Chanu_Sukarno的代码，你可以简单地将一个worker函数（或字符串）传递给这个函数，它将在web worker中执行它：

async function doWorkerTask(workerFunction, input, buffers) {
  // Create worker
  let fnString = '(' + workerFunction.toString().replace('"use strict";', '') + ')();';
  let workerBlob = new Blob([fnString]);
  let workerBlobURL = window.URL.createObjectURL(workerBlob, { type: 'application/javascript; charset=utf-8' });
  let worker = new Worker(workerBlobURL);

  // Run worker
  return await new Promise(function(resolve, reject) {
    worker.onmessage = function(e) { resolve(e.data); };
    worker.postMessage(input, buffers);
  });
}

以下是如何使用它的示例：

function myTask() {
  self.onmessage = function(e) {
    // do stuff with `e.data`, then:
    self.postMessage("my response");
    self.close();
  }
}
let output = await doWorkerTask(myTask, input, inputBuffers);
// now you can do something with `output` (which will be equal to "my response")

在 nodejs 中，doWorkerTask如下所示：

async function doWorkerTask(workerFunction, input, buffers) {
  let Worker = require('webworker-threads').Worker;
  let worker = new Worker(workerFunction);

  // Run worker
  return await new Promise(function(resolve, reject) {
    worker.onmessage = function(e) { resolve(e.data); };
    worker.postMessage(input, buffers);
  });
}

Answer 8

您可以通过将responseType更改为"text"或"arraybuffer"来获取 objectURL 中的实际数据，而不仅仅是blob。

以下是text/javascript至blob至objectURL的{em>来回转换，返回blob或text/javascript

_{如果您想知道，我使用它来生成没有外部文件的网络工作者

您可以使用它来返回二进制内容，例如YouTube视频;）（来自＆lt; video＆gt;标记资源属性）}

var blob = new Blob(['self.onmessage=function(e){postMessage(e)}'],{type: 'text/javascript'});   //->console: (object)   Blob {size: 42, type: "text/javascript", slice: function}

var obju = URL.createObjectURL(js_blob); //->console:  "blob:http%3A//stackoverflow.com/02e79c2b-025a-4293-be0f-f121dd57ccf7"

var xhr = new XMLHttpRequest();
xhr.open('GET', 'blob:http%3A//stackoverflow.com/02e79c2b-025a-4293-be0f-f121dd57ccf7', true);
xhr.responseType = 'text'; /* or "blob" */
xhr.onreadystatechange = function(){
  if(xhr.DONE !== xhr.readyState) return;

  console.log(xhr.response);
}
xhr.send();

/*
  responseType "blob" ->console: (object)   Blob {size: 42, type: "text/javascript", slice: function}
  responseType "text" ->console: (text)     'self.onmessage=function(e){postMessage(e)}'
*/

Answer 9

使用我的小插件https://github.com/zevero/worker-create

var worker_url = Worker.create("self.postMessage('Example post from Worker');");
var worker = new Worker(worker_url);

但你也可以给它一个功能。

如何从字符串创建Web Worker

9 个答案:

摘要

兼容性

后备1：数据URI

后退2：Eval