JSFiddle - React, Tailwind, and code Playground

HTML

<input type="textbox" id="partNumber" margin="20px" >
<input type="textbox" id="quantity" onfocus="saveOldQuantity();">
<input type="button" id="quantity" value="ok" onClick="validatePart(this);"/>

JavaScript

function validatePart() {
    console.log('validating part');
    alert('invalid part!');
    $('#partNumber').focus();
}

function saveOldQuanitity() {
    console.log('saving old quantity');
}