Q:

On click open another div with same data-index

Below, you can see that I have div class card bg-dark text-white with data-index 0, 1, 2. After that I have another div elements, with class over-menu active and their data-index 0, 1, 2. 
I have not tried anything so far because I do not how to do it.
 <div class="card bg-dark text-white" data-index="0">
 <div class="card bg-dark text-white" data-index="1">
 <div class="card bg-dark text-white" data-index="2">

<div class="over-menu active" data-index="0">
<div class="over-menu active" data-index="1">
<div class="over-menu active" data-index="2">

What I want to achieve is the next: When I click on a div class card bg-dark text-white with data-index 0 to open me the div class over-menu active with data-index 0, same for when data-index is 1, 2,...
Below is the code, can you please tell me how can I achieve that.

A:

When the card div is clicked, you can find the data value from the clicked div, and then iterate over over-menu divs to find the div with corresponding data value:
$('.card').click(function(){
  var _val = $(this).data('index');
  $('.over-menu').each(function(){
     if (_val === $(this).data('index')){
       //do something
      }
  });
});

