JSFiddle - React, Tailwind, and code Playground

HTML

<form action="">
<input type="radio" name="sex" value="male">Male<br>
<input type="radio" name="sex" value="female">Female <br/>
Age: <input type="text" name="age"><br>
</form>

JavaScript

$('input[type=radio]').click(function () {
    var $this = $(this);
    var sex = $(this).val();
    if (sex == "female") {
    // disable input
    $('input[name=age]').fadeOut(400, function () {
        $('input[name=age]').prop('disabled', true);
        $(this).css('background', '#c0c0c0').fadeIn("slow", function () {
            // Animation complete
        });
    });
    } else {
        //enable input
        $('input[name=age]').prop('disabled', false);
        $('input[name=age]').css('background', '#ffffff');
    }
});