JSFiddle - React, Tailwind, and code Playground

HTML

<input value="111"> 
<input value="222">
<input value="111"> 
<input value="333">

JavaScript

vals = [];
$('input').each(function () {
    var $this = $(this);
    var val = $this.val();
    vals.push(val);
});
for (var i = 0; i < vals.length; i++) {
    for (var n = 0; n < vals.length; n++) {
        if (n !== i) {
            if (vals[i] === vals[n]) {
                alert('There are similar values');
            }
        }
    }
}