JSFiddle - React, Tailwind, and code Playground

HTML

<div class="close-image" imageid="11" terminalid="100"></div>
<div class="close-image" imageid="10" terminalid="100"></div>
<div class="close-image" imageid="12" terminalid="100"></div>
<div class="close-image" imageid="11" terminalid="100"></div>
<div class="close-image" imageid="10" terminalid="100"></div>
<div class="close-image" imageid="12" terminalid="100"></div>

JavaScript

var res = [];
$('.close-image').each(function () {
    res.push($(this).attr('imageid'));
});

console.log(res, "With duplicates")
console.log(jQuery.unique(res), "Without duplicates")