CODE INSIDE

<script>
    function detectIE() {
        var ua = window.navigator.userAgent;

        var msie = ua.indexOf('MSIE ');
        if (msie > 0) {
            // IE 10 or older => return version number
            return parseInt(ua.substring(msie + 5, ua.indexOf('.', msie)), 10);
        }

        var trident = ua.indexOf('Trident/');
        if (trident > 0) {
            // IE 11 => return version number
            var rv = ua.indexOf('rv:');
            return parseInt(ua.substring(rv + 3, ua.indexOf('.', rv)), 10);
        }

        // other browser or edge
        return false;
    }

    // source: http://stackoverflow.com/questions/400212/how-do-i-copy-to-the-clipboard-in-javascript
    // enhancement with special case for IEs, otherwise the temp textarea will be visible
    function copyTextToClipboard(text) {
        if (detectIE()) {
            try {
                window.clipboardData.setData('Text', text);
                console.log('Copying text command via IE-setData');
            } catch (err) {
                console.log('Oops, unable to copy via IE-setData');
            }
        }
        else {

            var textArea = document.createElement("textarea");

            //
            //  This styling is an extra step which is likely not required. 
            //
            // Why is it here? To ensure:
            // 1. the element is able to have focus and selection.
            // 2. if element was to flash render it has minimal visual impact.
            // 3. less flakyness with selection and copying which might occur if
            //    the textarea element is not visible.
            //
            // The likelihood is the element won't even render, not even a flash,
            // so some of these are just precautions. 
            // 
            // However in IE the element
            // is visible whilst the popup box asking the user for permission for
            // the web page to copy to the clipboard. To prevent this, we are using 
            // the detectIE workaround.

            // Place in top-left corner of screen regardless of scroll position.
            textArea.style.position = 'fixed';
            textArea.style.top = 0;
            textArea.style.left = 0;

            // Ensure it has a small width and height. Setting to 1px / 1em
            // doesn't work as this gives a negative w/h on some browsers.
            textArea.style.width = '2em';
            textArea.style.height = '2em';

            // We don't need padding, reducing the size if it does flash render.
            textArea.style.padding = 0;

            // Clean up any borders.
            textArea.style.border = 'none';
            textArea.style.outline = 'none';
            textArea.style.boxShadow = 'none';

            // Avoid flash of white box if rendered for any reason.
            textArea.style.background = 'transparent';


            textArea.value = text;

            document.body.appendChild(textArea);

            textArea.select();

            try {
                var successful = document.execCommand('copy');
                var msg = successful ? 'successful' : 'unsuccessful';
                console.log('Copying text command was ' + msg);
            } catch (err) {
                console.log('Oops, unable to copy');
            }

            document.body.removeChild(textArea);
        }

    }
</script>

<button type="button" onclick="copyTextToClipboard('Foobar!')">
	Set Foobar to clipboard
</button>