While developing a Chrome extension you can come up with the situation to copy text to clipboard. I was searching over internet since I found following code snippet. It works like a charm.

function copyToClipboard( text ){
			  	var copyDiv = document.createElement('div');
				copyDiv.contentEditable = true;
				document.body.appendChild(copyDiv);
				copyDiv.innerHTML = text;
				copyDiv.unselectable = "off";
				copyDiv.focus();
				document.execCommand('SelectAll');
				document.execCommand("Copy", false, null);
				document.body.removeChild(copyDiv);
			}