Source Code: (back to article)
<input type="file" id="textInput" />
<div id="textOutput">Upload a text file please</div>

<script>
document.getElementById('textInput').addEventListener('change', function(event) {
const file = event.target.files[0];
const reader = new FileReader();
reader.onload = function(e) {
document.getElementById('textOutput').innerHTML = e.target.result;
};
reader.readAsText(file);
});
</script>