JSFiddle - React, Tailwind, and code Playground

by Barry Margolin

HTML

<input type="text" id="inputText" />
<br/>
<input type="button" value="Validate" onclick="validate()" />

JavaScript

function validate() {
    var inputText = document.getElementById("inputText").value;
    if (/[^A-Za-z0-9\s)(\][._&-]/.test(inputText)) {
        alert('Field name should be alphanumeric and alllowed  special characters _ . - [ ] ( ) &');
    }
    if (/^[^A-Za-z0-9]/.test(inputText)) {
        alert('Field name must start with an alphanumeric');
    }
}