JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="isValid" onkeyup="isValid()" />
<p><span id="results"></span></p>

CSS

#results {color:red}

JavaScript

var result;
var array = [ "admin", "admin1", "administrator" ];

function isValid(){
    $('#results').text("")
    $('#isValid').css('background-color', 'white');
    result = $.inArray($('#isValid').val().toLowerCase(), array);
    if (result > -1) {
        $('#results').html("This word is not acceptable!");
        $('#isValid').css('background-color', 'red');
    }
}