据我所知,web worker需要写在一个单独的JavaScript文件中,并像这样调用:

new Worker('longrunning.js')

我正在使用闭包编译器来合并和缩小我所有的JavaScript源代码,我不希望将我的worker放在单独的文件中进行分发。有什么办法可以做到吗?

new Worker(function() {
    //Long-running work here
});

既然一级函数对JavaScript如此重要,为什么标准的后台工作方式必须从web服务器加载整个其他JavaScript文件呢?


当前回答

将Adria的响应放在一个可复制粘贴的函数中,该函数适用于当前的Chrome和FF,但不适用于IE10 (worker from blob会导致安全错误)。

var newWorker = function (funcObj) {
    // Build a worker from an anonymous function body
    var blobURL = URL.createObjectURL(new Blob(
        ['(', funcObj.toString(), ')()'],
        {type: 'application/javascript'}
     ));

    var worker = new Worker(blobURL);

    // Won't be needing this anymore
    URL.revokeObjectURL(blobURL);

    return worker;
}

下面是一个工作示例http://jsfiddle.net/ubershmekel/YYzvr/

其他回答

对于Node.js实现,可以使用以下对Trincot答案的改编。再次注意,Function.prototype.callAsWorker()接受一个thisArg和参数,就像Function.prototype.call()一样,并返回一个承诺。

const { Worker } = require ( 'worker_threads' );

Function.prototype.callAsWorker = function ( ...args ) {
    return new Promise( ( resolve, reject ) => {

        const code = `
            const { parentPort, workerData } = require ( 'worker_threads' );
            parentPort.postMessage( ( ${this.toString()} ).call( ...workerData ) )
        `;
        const worker = new Worker( code, { eval: true, workerData: args } );
            
        worker.on('message', ( msg ) => { resolve( msg ), worker.terminate() } );
        worker.on('error', ( err ) => { reject( err ), worker.terminate() } );
        worker.on('exit', ( code ) => {
            if ( code !== 0 ) {
                reject( new Error( `Worker stopped with exit code ${code}.` ) );
            }
        });

    });
}

// Demo
function add( ...nums ) {
    return nums.reduce( ( a, b ) => a + b );
}

// Let the worker execute the above function, with the specified arguments
let result = await add.callAsWorker( null, 1, 2, 3 );
console.log( 'result: ', result );

我的看法是:

function BuildWorker(fn){
   var str = fn.toString().match(/^[^{]+{([\s\S]+)}\s*$/m)[1];
   return  new Worker(window.URL.createObjectURL(
                new Blob([str],{type:'text/javascript'})));
}

function createAsyncWorker(fn){
    
    // asyncworker=createAsyncWorker(function(){
    //     importScripts('my_otherscript.js');
    //     self.onmessage = function([arg1,arg2]) {
    //         self.postMessage('msg from worker');
    //     };
    // })
    // await asyncworker.postMessage('arg1','value')
    // await asyncworker.postMessage('arg1','value')
    // asyncworker.worker.terminate()
    
    var worker = BuildWorker(fn);

    function postMessage(...message){
        let external={}, promise= new Promise((resolve,reject)=>{external.resolve=resolve;external.reject=reject;})
        worker.onmessage = function(message){ external.resolve(message.data)};
        worker.postMessage(message); // Start the worker.
        return promise;
    }

    return {worker,postMessage};
}

使用的例子:

autoarima = createAsyncWorker(function(){
    importScripts("https://127.0.0.1:11000/arima.js")
    
    self.onmessage=(message)=>{
        let [action,arg1,arg2]=message.data
        if(action=='load')
        {
            ARIMAPromise.then(ARIMA1 => {
                ARIMA=ARIMA1
                autoarima = new ARIMA({ auto: true });
                //   const ts = Array(10).fill(0).map((_, i) => i + Math.random() / 5)
                //   const arima = new ARIMA({ p: 2, d: 1, q: 2, P: 0, D: 0, Q: 0, S: 0, verbose: false }).train(ts)
                //   const [pred, errors] = arima.predict(10)
                postMessage('ok')
            });
        }
        if(action=='fit')
        {
            autoarima.fit(arg1)
            postMessage('ok')
        }
        if(action=='predict')
        {
            postMessage(autoarima.predict(arg1,arg2)) 
        }
    };
})
autoarima.terminate=function(){  this.worker.terminate(); }
autoarima.load=async function(...args){return await this.postMessage('load',...args)}
autoarima.fit=async function(...args){return await this.postMessage('fit',...args)}
autoarima.predict=async function(...args){return await this.postMessage('predict',...args)}

await autoarima.load()
await autoarima.fit(b_values)
await autoarima.predict(1)

是的,这是可能的,我做到了使用Blob文件和传递回调

我将向您展示我编写的一个类是做什么的,以及它如何在后台管理回调的执行。

首先,你要实例化GenericWebWorker,使用你想要传递给回调的任何数据,这些数据将在WebWorker中执行,包括你想要使用的函数,在这种情况下,一个数字,一个日期和一个叫做blocker的函数

var worker = new GenericWebWorker(100, new Date(), blocker)

这个阻塞器函数将在n毫秒内执行一个无限while

function blocker (ms) {
    var now = new Date().getTime();
    while(true) {
        if (new Date().getTime() > now +ms)
            return;
    }   
}

然后像这样用

worker.exec((num, date, fnBlocker) => {
    /*Everithing here does not block the main thread
      and this callback has access to the number, date and the blocker */
    fnBlocker(10000) //All of this run in backgrownd
    return num*10

}).then(d => console.log(d)) //Print 1000

现在,是时候看看下面例子中的神奇之处了

/*https://github.com/fercarvo/GenericWebWorker*/ class GenericWebWorker { constructor(...ags) { this.args = ags.map(a => (typeof a == 'function') ? {type:'fn', fn:a.toString()} : a) } async exec(cb) { var wk_string = this.worker.toString(); wk_string = wk_string.substring(wk_string.indexOf('{') + 1, wk_string.lastIndexOf('}')); var wk_link = window.URL.createObjectURL( new Blob([ wk_string ]) ); var wk = new Worker(wk_link); wk.postMessage({ callback: cb.toString(), args: this.args }); var resultado = await new Promise((next, error) => { wk.onmessage = e => (e.data && e.data.error) ? error(e.data.error) : next(e.data); wk.onerror = e => error(e.message); }) wk.terminate(); window.URL.revokeObjectURL(wk_link); return resultado } async parallel(arr, cb) { var res = [...arr].map(it => new GenericWebWorker(it, ...this.args).exec(cb)) var all = await Promise.all(res) return all } worker() { onmessage = async function (e) { try { var cb = new Function(`return ${e.data.callback}`)(); var args = e.data.args.map(p => (p.type == 'fn') ? new Function(`return ${p.fn}`)() : p); try { var result = await cb.apply(this, args); //If it is a promise or async function return postMessage(result) } catch (e) { throw new Error(`CallbackError: ${e}`) } } catch (e) { postMessage({error: e.message}) } } } } function blocker (ms) { var now = new Date().getTime(); while(true) { if (new Date().getTime() > now +ms) return; } } setInterval(()=> console.log("Not blocked " + Math.random()), 1000) console.log("\n\nstarting blocking code in Worker\n\n") var worker = new GenericWebWorker(100, new Date(), blocker) worker.exec((num, date, fnBlocker) => { fnBlocker(7000) //All of this run in backgrownd return num*10 }) .then(d => console.log(`\n\nEnd of blocking code: result ${d}\n\n`)) //Print 1000

我发现CodePen目前不语法高亮内联<script>标签,不是type="text/javascript"(或没有类型属性)。

因此,我设计了一个类似但略有不同的解决方案,使用带break的标记块,这是摆脱<script>标记而不创建包装器函数(这是不必要的)的唯一方法。

<!DOCTYPE html> <script id="worker1"> worker: { // Labeled block wrapper if (typeof window === 'object') break worker; // Bail if we're not a Worker self.onmessage = function(e) { self.postMessage('msg from worker'); }; // Rest of your worker code goes here. } </script> <script> var blob = new Blob([ document.querySelector('#worker1').textContent ], { type: "text/javascript" }) // Note: window.webkitURL.createObjectURL() in Chrome 10+. var worker = new Worker(window.URL.createObjectURL(blob)); worker.onmessage = function(e) { console.log("Received: " + e.data); } worker.postMessage("hello"); // Start the worker. </script>

这是一个有点离题的答案,但是……您可能不需要使用网络工作者来处理浏览器上的长时间工作。

让我们假设你想要运行几次繁重的计算(就像你对数组做的那样):

const heavyFct = () => {let i = 0; while(i<1e8) {++i}}

for (let i = 0; i < 100; ++i) {
  heavyFct();
}

这将冻结您的浏览器。

为了避免这种情况,我们可以这样依赖setTimeout:

const desync = (i = 0) => {
  if (i >= 100) {return}
  heavyFct();
  setTimeout(() => desync(i + 1), 0);
}
desync();

现在,您可以在不冻结计算机的情况下运行繁重的计算