JSFiddle - React, Tailwind, and code Playground

HTML

<input type="button" value="1"/>
<input type="button" value="2"/>
<input type="button" value="3"/>
<input type="button" value="4"/>
<input type="button" value="5"/><br>
<input type="text"/>

JavaScript

$('input:button').click(function(event) {
    $('input:text').val(function(index, val) {
        return val + event.target.value;
    });
});