Disallow Selection in web-page using JavaScript

Sometimes, we do not want people to copy the text on some of our web pages, here is a script which prevents user (not advanced users) from selecting the text.
For better results put the JavaScript code inline and not in a separate JS file.

Code:

// specify allowed tags for some browsers
var allowedTags=["input", "textarea", "select"]

allowedTags=allowedTags.join("|");

function disableselect(e)
{
    if (allowedTags.indexOf(e.target.tagName.toLowerCase()) == -1)
        return false;
}

function reEnable()
{
    return true;
}

if (typeof document.onselectstart != "undefined")
    document.onselectstart=new Function ("return false");
else
{
    document.onmousedown=disableselect;
    document.onmouseup=reEnable;
}