var text = $("#discountCode").get(0); // Grab the node of the element

var selection = window.getSelection(); // Get the Selection object

var range = document.createRange(); // Create a new range

range.selectNodeContents(text); // Select the content of the node from line 1

selection.removeAllRanges(); // Delete any old ranges

selection.addRange(range); // Add the range to selection

document.execCommand('copy'); // Execute the command