JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
<input name="+" type="button" id="+" onclick="addInput()" value="+" label="+" />
<input name="-" type="button" id="-" onclick="subtractInput()" value="-" label="-" />
</div>

JavaScript

var countBox = 1;

    addInput = function() {
        var breakNode = document.createElement("br");
        breakNode.className = countBox.toString();
        
        var input = document.createElement("input");
        input.type = "text";
        input.className = countBox.toString();
        input.value = "#" + countBox.toString();
        
        var container = document.getElementById('container');
        container.appendChild(breakNode);
        container.appendChild(input);
        
        countBox += 1;
    }

    subtractInput = function() {
        countBox -= 1;
        
        // There will be 2 elements: 1 input, 1 br.
        var elements = document.getElementsByClassName(countBox.toString());
        var input = elements[1];
        var br = elements[0];
        
        input.parentNode.removeChild(input);
        br.parentNode.removeChild(br);
    }