JSFiddle - React, Tailwind, and code Playground

by sdgluck

HTML

<div imageid="10"></div>
<div imageid="10"></div>
<div imageid="11"></div>
<div imageid="12"></div>

<div id="result"></div>

JavaScript

var elements = document.querySelectorAll('[imageid]');
var ids = [];

for(var i = 0; i < elements.length; i++) {
  var element = elements[i];
  var elementImageId = element.getAttribute('imageid');
  
  if(ids.indexOf(elementImageId) === -1) {
    ids.push(elementImageId);
  }
};

document.querySelector('#result').innerHTML = JSON.stringify(ids);