Typescript/Javascript load existing file without user interaction

Question

I've seen many examples making use of

<input type="file" id="file"/>

and then something like

let $img: any = document.querySelector('#file');

if (typeof (FileReader) !== 'undefined') {
    let reader = new FileReader();

    reader.onload = (e: any) => {
      this.pdfSrc = e.target.result;
    };

    reader.readAsArrayBuffer($img.files[0]);
}

However, I know the file path and I just want to get that without any user interaction. In the example, $img.files[0] is a Blob, so it would seem that I would need to create a new Blob or File object from my known file path, but I can't figure out how to do that. I do not want to create a new file, just an object from the existing file. I would think this would be quite straight-forward, so I'm hoping I'm just missing something easy. Thanks!

It sounds like it would be a security hole if the browser let javascripts just load any file it liked, wouldn't it? — Chris Charles
– Chris Charles, Commented Feb 21, 2018 at 17:54
There is no way to select a file without the user selecting it. — epascarello
– epascarello, Commented Feb 21, 2018 at 17:54
So it sounds like the correct way to do this is to have javascript load the file from the server. — Tim
– Tim, Commented Feb 21, 2018 at 17:57
My search-fu must be weak today. I'm sure I've seen this question a dozen times; not finding them, though. Hopefully someone else will. — T.J. Crowder
– T.J. Crowder, Commented Feb 21, 2018 at 18:02

T.J. Crowder · Accepted Answer · 2018-02-21 18:00:11Z

1

No, you cannot do that. The user has to identify the file to load (via the input type="file", drag-and-drop, etc.). You cannot pre-specify the filename, nor initiate the file load, without the user's intervention. It would be a massive security hole.

You can load files from your server, or from other servers allowing your origin via Cross-Origin Resource Sharing, but not from the user's machine.

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