如何选择文本框中的所有文本并使用JavaScript / jQuery将其复制到剪贴板？

I have a textbox with an 'Add to clipboard' button next to it. Whenever the copy to clipboard button is pressed, I want the contents of the clipboard to get copied to the clipboard, and work in a cross browser way across Internet Explorer, Firefox, Chrome, Opera, etc. I can use I have a textbox with an 'Add to clipboard' but