Passing Uint8 array to PDF.js not working

Question

I need to use PDF.js local, without a webserver. Just need to display a PDF which is in the same directory. Found this link here and also read in the FAQ that you can pass a Uint8 Array to PDF.js. I'm using filereader() to read the file. But I'm getting "Invalid PDF structure" error message. The PDF is ok - I've uploaded the whole thing to a webserver for testing. When opening the PDF with viewer.html online its working. What am I missing?

This is my code so far:

    var file = new File(["compressed.tracemonkey-pldi-09.pdf"], "compressed.tracemonkey-pldi-09.pdf", {type: 'application/pdf'});

    var fileReader = new FileReader();  

    fileReader.onload = function() {
        var typedarray = new Uint8Array(fileReader.result);
        pdfjsLib.getDocument(typedarray).then(function(pdf) {
           //do something
        });

    };

    fileReader.readAsArrayBuffer(file);