JSFiddle - React, Tailwind, and code Playground

HTML

<div class="copy-button green"></div> 
<div class="copy-button white"></div> 
<div class="copy-button red"></div>

CSS

.copy-button {
    color:red;
    width:120px;
    height:120px;
    float: left;
    margin: 0 8px;
}

.green {
  background:#2ecc71;
}

.white {
  background:#fff;
}

.red {
  background:#e74c3c;
}

JavaScript

var color = '';

$('.copy-button').click(function() {
    var x = $(this).css('backgroundColor');
    hexc(x);
    alert(color);
})

function hexc(colorVal) {
    var parts = colorVal.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);
    delete(parts[0]);
    for (var i = 1; i <= 3; ++i) {
        parts[i] = parseInt(parts[i]).toString(16);
        if (parts[i].length == 1) parts[i] = '0' + parts[i];
    }
    color = '#' + parts.join('');
    document.execCommand("copy");
}