JSFiddle - React, Tailwind, and code Playground

HTML

<div id="dump"></div>

<button>Click</button>

CSS

#dump {
 height: 100px;
width: 200px; 
border: 1px solid black;    
}

JavaScript

$(document).ready(function(){
    var newArray = [];
    newArray['first'] = 1;
    newArray['second'] = 1;
    
    $('button').click(function(){
        if($.inArray(1, newArray) != -1){
            $('#dump').css('border', '1px solid red');
        } else {
            $('#dump').css('border', '1px solid blue');
        }
    });
});