Read a local text file using Javascript

You can use a FileReader object to read text file here is example code:

  <div id="page-wrapper">

        <h1>Text File Reader</h1>
        <div>
            Select a text file: 
            <input type="file" id="fileInput">
        </div>
        <pre id="fileDisplayArea"><pre>

    </div>
<script>
window.onload = function() {
        var fileInput = document.getElementById('fileInput');
        var fileDisplayArea = document.getElementById('fileDisplayArea');

        fileInput.addEventListener('change', function(e) {
            var file = fileInput.files[0];
            var textType = /text.*/;

            if (file.type.match(textType)) {
                var reader = new FileReader();

                reader.onload = function(e) {
                    fileDisplayArea.innerText = reader.result;
                }

                reader.readAsText(file);    
            } else {
                fileDisplayArea.innerText = "File not supported!"
            }
        });
}

</script>

Here is the codepen demo

If you have a fixed file to read every time your application load then you can use this code :

<script>
var fileDisplayArea = document.getElementById('fileDisplayArea');
function readTextFile(file)
{
    var rawFile = new XMLHttpRequest();
    rawFile.open("GET", file, false);
    rawFile.onreadystatechange = function ()
    {
        if(rawFile.readyState === 4)
        {
            if(rawFile.status === 200 || rawFile.status == 0)
            {
                var allText = rawFile.responseText;
                fileDisplayArea.innerText = allText 
            }
        }
    }
    rawFile.send(null);
}

readTextFile("file:///C:/your/path/to/file.txt");
</script>