JSFiddle - React, Tailwind, and code Playground

HTML

<input id="xstart" type="number" min="0" max = "100"/>
<input id="ystart" type="number" min="0" max = "100"/>
<input id="zstart" type="number" min="0" max = "100"/>

<input type="button" id="clickit" value="test" />

<p id="result"></p>

JavaScript

var xInput = document.getElementById('xstart'),
    yInput = document.getElementById('ystart'),
    zInput = document.getElementById('zstart');

document.getElementById('clickit').addEventListener('click', myFunc);

function myFunc(){
    var xstart = parseInt( xInput.value ),
        ystart = parseInt( yInput.value ),
        zstart = parseInt( zInput.value );
    alert( xstart + ', ' + ystart + ', ' + zstart);
}