Modify Clipboard content after copy event: JavaScript, jQuery

The currently accepted answer is overly complicated, and causes weird behavior where a user's selection is removed after copy.

Here is a much simpler solution:

document.addEventListener('copy', function(e){
  var text = window.getSelection().toString().replace(/[\n\r]+/g, '');
  e.clipboardData.setData('text/plain', text);
  e.preventDefault();
});

To resolve this issue what I have done on copy event I have bind a function i.e. copyToClipboard which creates a textarea at run time, copy modified clipboard data to this text area and then execute a 'CUT' command (to avoid recursive call on copy event). And finally deleting textarea element in finally block.

Code:

$(document).bind('copy', function () {
            var text = window.getSelection().toString().replace(/[\n\r]+/g, '');
            copyToClipboard(text);
        });

        function copyToClipboard(text) {
                var textarea = document.createElement("textarea");
                textarea.textContent = text;
                textarea.style.position = "fixed";
                document.body.appendChild(textarea);
                textarea.select();
                try {
                    return document.execCommand("cut");
                } catch (ex) {
                    console.warn("Copy to clipboard failed.", ex);
                    return false;
                } finally {
                    document.body.removeChild(textarea);
                }
        }

There are two things I can find out.

1. clipboardData object will be in callback object e passed not in window.
2. the correct syntax for setData is like below.

For further reference copy Event MDN

document.addEventListener('copy', function(e) {
  console.log('copied');
  e.clipboardData.setData('text/plain', 'Hello World!');
  e.preventDefault();
});