JSFiddle - React, Tailwind, and code Playground

by Rajesh Kakawat

HTML

<select id="indexBookSearch">
    <option value="">SELECT</option>
    <option value="A">A</option>
    <option value="B">B</option>
    <option value="C">C</option>
</select>
<select id="indexTagSearch">
    <option value="">SELECT</option>
    <option value="A">A</option>
    <option value="B">B</option>
    <option value="C">C</option>
</select>
<input type="button" id="btn" value="check">

JavaScript

$('#btn').click(function () {
    var book_id = $('#indexBookSearch');
    var tag_id = $('#indexTagSearch');

    if ((book_id.val().trim() === "") || (tag_id.val().trim() === "")) {
        alert('true');
    }
})