Pass submited file to web worker by refference with as little overhead as possible

Question

I will have a web worker to parse huge text file (200000 lines, simple syntax though). I expect user to submit that file wia drag'n'drop or otherwise, obtaining a File object:

   var work = new Worker("parser.js")
   document.addEventListener("drop", function(e) {
       e.preventDefault();
       var dt    = e.dataTransfer;
       var files = dt.files;
       if(files.length>0) {
         var firstFile = files[0]
         var reader = new FileReader();
         //SEND FILE TO WORKER?
       }
   });

I heard of Transferable objects. Is there a way to transfer file to Worker? In a way that GUI thread will not be slowed by reading the file?

There is a great tutorial on this here: http://www.html5rocks.com/en/tutorials/file/filesystem-sync/ , you can even handle the fileReader on the worker — juvian, Oct 23 '15 at 15:35

Dark Falcon · Accepted Answer · 2015-10-23T15:37:14.370

9

Some browsers (can't find a compatibility table) support passing File objects through the web worker postMessage because they now use the structured clone algorithm to handle the message parameters. This would probably be the most efficient method for those browsers which support it.

Further research seems to indicate that structured cloning is supposed to be available on: Chrome 13+, Firefox 8+, IE10+, Opera 11.5+, Safari 5.1+

edited Oct 23 '15 at 15:37

answered Oct 23 '15 at 15:30

Dark Falcon

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And that would basically mean the file is passed before even being opened, right? – Tomáš Zato Oct 23 '15 at 16:12

Pass submited file to web worker by refference with as little overhead as possible

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