JSFiddle - React, Tailwind, and code Playground

by TJ VanToll

HTML

<form>
    <label>
        Username:
        <input required>
    </label>
    <button>Submit</button>
</form>

CSS

body { margin: 20px; }

JavaScript

document.querySelector( "input" )
    .setCustomValidity( "This username is not available" );
document.querySelector( "button" ).click();