JSFiddle - React, Tailwind, and code Playground

HTML

<input type="file" id="upload" />

<div class="bg">

</div>

CSS

.bg{
    width: 100%;
    height: 240px;
    border: 1px solid #ccc;
}

JavaScript

$(document).on('change', '#upload', addBackgroundImage);

function addBackgroundImage(event) {
    var reader = new FileReader();

    reader.onloadend = function(event) {     
            var base64 = reader.result;
            $('.bg').css('background-image', 'url('+base64+')');
       
    }
    reader.readAsDataURL(event.target.files[0]);
    
    $('#upload').val('');
}