JSFiddle - React, Tailwind, and code Playground

HTML

<input name="names[]" class="names"  id="names" /> 
<input name="names[]" class="names"  id="names" /> 
<input name="names[]" class="names"  id="names" />

JavaScript

$(document).ready(function() {
    alert(
        "#names\t\t\t\t\t:   " + $("#names").size() + 
        "\n.names\t\t\t\t\t:   " + $(".names").size() + 
        "\nname=\"names\\\\[\\\\]\"\t\t:   " + $("input[name=names\\[\\]]").size()
    );
});