问在可杀死的“线程”中运行JS；检测和取消长期运行的进程。

EN

var worker, activeMsgs, userTypingTimeout, deathRowTimer;
killWorker(); // Also creates the first one

grammarTextarea.onchange = grammarTextarea.oninput = function(){
  // Wait until the user has not typed for 500ms before parsing
  clearTimeout(userTypingTimeout);
  userTypingTimeout = setTimeout(askWorkerToParse,500);
}

function askWorkerToParse(){
  worker.postMessage({action:'parseInput',input:grammarTextarea.value});
  activeMsgs++;                                // Another message is in flight
  clearTimeout(deathRowTimer);                 // Restart the timer
  deathRowTimer = setTimeout(killWorker,2000); // It must finish quickly
};

function killWorker(){
  if (worker) worker.terminate();   // This kills the thread
  worker = new Worker('worker.js')  // Create a new worker thread
  activeMsgs = 0;                   // No messages are pending on this new one
  worker.addEventListener('message',handleWorkerResponse,false);
}

function handleWorkerResponse(evt){
  // If this is the last message, it responded in time: it gets to live.
  if (--activeMsgs==0) clearTimeout(deathRowTimer);
  // **Process the evt.data.results from the worker**
},false);

importScripts('utils.js') // Each worker is a blank slate; must load libs

self.addEventListener('message',function(evt){
  var data = evt.data;
  switch(data.action){
    case 'parseInput':
      // Actually do the work (which sometimes goes bad and locks up)
      var parseResults = parse(data.input);

      // Send the results back to the main thread.
      self.postMessage({kind:'parse-results',results:parseResults});
    break;
  }
},false);