Can Javascript check a file for content changes?

Question

Example:

I have

var r = new FileReader();
    r.onload = function(e) {
        drawGraph(r.result);
    }
    r.readAsText(f);

drawing a graph from the file f input by the user.

Is there a way to check to see if the file f has been changed and then re load it's content without needing for the user to pick the file again?

Could I refresh the file? instead of waiting for it to change, just update the graph periodically automatically, or do I need user input for that? — Damien King-Acevedo, Mar 17 '15 at 18:03
are you building a web app? i think you can do this in javascript with a chrome app. — Jeff, Mar 17 '15 at 18:06

score 3 · Accepted Answer · edited May 23 '17 at 11:56

Yes, this can be achieved using Node.js's filesystem API which provides a "watch" function

NodeJS Filesystem API docs: https://nodejs.org/api/fs.html

Similar question: Observe file changes with node.js

fs.watch('somedir', function (event, filename) {
    console.log('event is: ' + event);
    if (filename) {
        console.log('filename provided: ' + filename);
    } else {
        console.log('filename not provided');
    }
});

Can Javascript check a file for content changes?

1 Answers1

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