How to upload a file from pre-defined location in pc onto a webpage? without user intervension

Question

I can have the user upload a file on a webpage using <input type='file' accept='text/plain' onchange='ReadTheTextfile(event)'>. and then use javascript: FileReader, reader.readAsText(event.target.files[0]); etc

but I already know that I want to read a file, which I already uploaded to the webserver.

How can I determine by myself which file I want to upload / read ? XMLHttpRequest ?

I don't want to read a file from the user's pc. I want to read a file from the server, where my html files are also hosted.

Answer 1

You can retrive it via ajax call as follows.

function getFileFromServer(url, doneCallback) {
    var xhr;

    xhr = new XMLHttpRequest();
    xhr.onreadystatechange = handleStateChange;
    xhr.open("GET", url, true);
    xhr.send();

    function handleStateChange() {
        if (xhr.readyState === 4) {
            doneCallback(xhr.status == 200 ? xhr.responseText : null);
        }
    }
}

getFileFromServer("path/to/file", function(text) {
    if (text === null) {
        // An error occurred
    }
    else {
        // `text` is the file text
    }
});

Reference - https://stackoverflow.com/a/13329900/9640177