JSFiddle - React, Tailwind, and code Playground

HTML

<form id="file-form" method="POST">
    <input type="file" id="file-select" />
</form>
<button onclick="getImage()" id="upload-button">Convert</button>

JavaScript

function getImage() {

    var reader = new FileReader();
    var f = document.getElementById("file-select").files;

    reader.onloadend = function () {
        console.log(reader.result);
    }
    reader.readAsDataURL(f[0]);

}