javascript – How to add extra info to copied web text-ThrowExceptions

Exception or error:

Some websites now use a JavaScript service from Tynt that appends text to copied content.

If you copy text from a site using this and then paste you get a link to the original content at the bottom of the text.

Tynt also tracks this as it happens. It’s a neat trick well done.

Their script for doing this is impressive – rather than try to manipulate the clipboard (which only older versions of IE lets them do by default and which should always be turned off) they manipulate the actual selection.

So when you select a block of text the extra content is added as a hidden <div> included in your selection. When you paste the extra style is ignored and the extra link appears.

This is actually fairly easy to do with simple blocks of text, but a nightmare when you consider all the selections possible across complex HTML in different browsers.

I’m developing a web application – I don’t want anyone to be able to track the content copied and I would like the extra info to contain something contextual, rather than just a link. Tynt’s service isn’t really appropriate in this case.

Does anyone know of an open source JavaScript library (maybe a jQuery plug in or similar) that provides similar functionality but that doesn’t expose internal application data?

How to solve:

2020 Update

Solution that works on all recent browsers.

document.addEventListener('copy', (event) => {
  const pagelink = `\n\nRead more at: ${document.location.href}`;
  event.clipboardData.setData('text', document.getSelection() + pagelink);
  event.preventDefault();
});
Lorem ipsum dolor sit amet, consectetur adipiscing elit.<br/>
<textarea name="textarea" rows="7" cols="50" placeholder="paste your copied text here"></textarea>

[Older post – before the 2020 update]

There are two main ways to add extra info to copied web text.

1. Manipulating the selection

The idea is to watch for the copy event, then append a hidden container with our extra info to the dom, and extend the selection to it.
This method is adapted from this article by c.bavota. Check also jitbit‘s version for more complex case.

  • Browser compatibility: All major browsers, IE > 8.
  • Demo: jsFiddle demo.
  • Javascript code:

    function addLink() {
        //Get the selected text and append the extra info
        var selection = window.getSelection(),
            pagelink = '<br /><br /> Read more at: ' + document.location.href,
            copytext = selection + pagelink,
            newdiv = document.createElement('div');

        //hide the newly created container
        newdiv.style.position = 'absolute';
        newdiv.style.left = '-99999px';

        //insert the container, fill it with the extended text, and define the new selection
        document.body.appendChild(newdiv);
        newdiv.innerHTML = copytext;
        selection.selectAllChildren(newdiv);

        window.setTimeout(function () {
            document.body.removeChild(newdiv);
        }, 100);
    }

    document.addEventListener('copy', addLink);

2. Manipulating the clipboard

The idea is to watch the copy event and directly modify the clipboard data. This is possible using the clipboardData property. Note that this property is available in all major browsers in read-only; the setData method is only available on IE.

  • Browser compatibility: IE > 4.
  • Demo: jsFiddle demo.
  • Javascript code:

    function addLink(event) {
        event.preventDefault();

        var pagelink = '\n\n Read more at: ' + document.location.href,
            copytext =  window.getSelection() + pagelink;

        if (window.clipboardData) {
            window.clipboardData.setData('Text', copytext);
        }
    }

    document.addEventListener('copy', addLink);

###

This is a vanilla javascript solution from a modified solution above but supports more browsers (cross browser method)

function addLink(e) {
    e.preventDefault();
    var pagelink = '\nRead more: ' + document.location.href,
    copytext =  window.getSelection() + pagelink;
    clipdata = e.clipboardData || window.clipboardData;
    if (clipdata) {
        clipdata.setData('Text', copytext);
    }
}
document.addEventListener('copy', addLink);

###

The shortest version for jQuery that I tested and is working is:

jQuery(document).on('copy', function(e)
{
  var sel = window.getSelection();
  var copyFooter = 
        "<br /><br /> Source: <a href='" + document.location.href + "'>" + document.location.href + "</a><br />© YourSite";
  var copyHolder = $('<div>', {html: sel+copyFooter, style: {position: 'absolute', left: '-99999px'}});
  $('body').append(copyHolder);
  sel.selectAllChildren( copyHolder[0] );
  window.setTimeout(function() {
      copyHolder.remove();
  },0);
});

###

Here is a plugin in jquery to do that
https://github.com/niklasvh/jquery.plugin.clipboard
From the project readme
“This script modifies the contents of a selection prior to a copy event being called, resulting in the copied selection being different from what the user selected.

This allows you to append/prepend content to the selection, such as copyright information or other content.

Released under MIT License”

###

Improving on the answer, restore selection after the alterations to prevent random selections after copy.

function addLink() {
    //Get the selected text and append the extra info
    var selection = window.getSelection(),
        pagelink = '<br /><br /> Read more at: ' + document.location.href,
        copytext = selection + pagelink,
        newdiv = document.createElement('div');
    var range = selection.getRangeAt(0); // edited according to @Vokiel's comment

    //hide the newly created container
    newdiv.style.position = 'absolute';
    newdiv.style.left = '-99999px';

    //insert the container, fill it with the extended text, and define the new selection
    document.body.appendChild(newdiv);
    newdiv.innerHTML = copytext;
    selection.selectAllChildren(newdiv);

    window.setTimeout(function () {
        document.body.removeChild(newdiv);
        selection.removeAllRanges();
        selection.addRange(range);
    }, 100);
}

document.addEventListener('copy', addLink);

###

Improvement for 2018

document.addEventListener('copy', function (e) {
    var selection = window.getSelection();
    e.clipboardData.setData('text/plain', $('<div/>').html(selection + "").text() + "\n\n" + 'Source: ' + document.location.href);
    e.clipboardData.setData('text/html', selection + '<br /><br />Source: <a href="' + document.location.href + '">' + document.title + '</a>');
    e.preventDefault();
});

###

Also a little shorter solution:

jQuery( document ).ready( function( $ )
    {
    function addLink()
    {
    var sel = window.getSelection();
    var pagelink = "<br /><br /> Source: <a href='" + document.location.href + "'>" + document.location.href + "</a><br />© text is here";
    var div = $( '<div>', {style: {position: 'absolute', left: '-99999px'}, html: sel + pagelink} );
    $( 'body' ).append( div );
    sel.selectAllChildren( div[0] );
    div.remove();
    }



document.oncopy = addLink;
} );

###

It’s a compilation of 2 answers above + compatibility with Microsoft Edge.

I’ve also added a restore of the original selection at the end, as it is expected by default in any browser.

function addCopyrightInfo() {
    //Get the selected text and append the extra info
    var selection, selectedNode, html;
    if (window.getSelection) {
        var selection = window.getSelection();
        if (selection.rangeCount) {
            selectedNode = selection.getRangeAt(0).startContainer.parentNode;
            var container = document.createElement("div");
            container.appendChild(selection.getRangeAt(0).cloneContents());
            html = container.innerHTML;
        }
    }
    else {
        console.debug("The text [selection] not found.")
        return;
    }

    // Save current selection to resore it back later.
    var range = selection.getRangeAt(0);

    if (!html)
        html = '' + selection;

    html += "<br/><br/><small><span>Source: </span><a target='_blank' title='" + document.title + "' href='" + document.location.href + "'>" + document.title + "</a></small><br/>";
    var newdiv = document.createElement('div');

    //hide the newly created container
    newdiv.style.position = 'absolute';
    newdiv.style.left = '-99999px';

    // Insert the container, fill it with the extended text, and define the new selection.
    selectedNode.appendChild(newdiv); // *For the Microsoft Edge browser so that the page wouldn't scroll to the bottom.

    newdiv.innerHTML = html;
    selection.selectAllChildren(newdiv);

    window.setTimeout(function () {
        selectedNode.removeChild(newdiv);
        selection.removeAllRanges();
        selection.addRange(range); // Restore original selection.
    }, 5); // Timeout is reduced to 10 msc for Microsoft Edge's sake so that it does not blink very noticeably.  
}

document.addEventListener('copy', addCopyrightInfo);

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