JSFiddle - React, Tailwind, and code Playground

HTML

<input type="file" id="file" name="file" enctype="multipart/form-data" />

JavaScript

document.getElementById('file').addEventListener('change', readFile, false);

       function readFile (evt) {
           var files = evt.target.files;
           var file = files[0];           
           var reader = new FileReader();
           reader.onload = function(event) {
             console.log(event.target.result);            
           }
           reader.readAsText(file)
        }