JSFiddle - React, Tailwind, and code Playground

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/dot-luv/jquery-ui.css">
<form>
    <input type="file" id="css-file" />
    <input type="text" id="css-url" value="eg. http://domain.com/style.css" />
    <button type="submit">Test</button>
</form>

JavaScript

$("form").submit(function(e) {
    $("#css-file, #css-url").each(function() {
        if(this.value.slice(-4) != ".css") {
            e.preventDefault();
            alert(this.value + " is not a .css file");
        }
    });
});