How do I disable text selection with CSS or JavaScript? [duplicate]

<div 
 style="-moz-user-select: none; -webkit-user-select: none; -ms-user-select:none; user-select:none;-o-user-select:none;" 
 unselectable="on"
 onselectstart="return false;" 
 onmousedown="return false;">
    Blabla
</div>

UPDATE January, 2017:

According to Can I use, the user-select is currently supported in all browsers except Internet Explorer 9 and earlier versions (but sadly still needs a vendor prefix).

All of the correct CSS variations are:

.noselect {
  -webkit-touch-callout: none; /* iOS Safari */
    -webkit-user-select: none; /* Safari */
     -khtml-user-select: none; /* Konqueror HTML */
       -moz-user-select: none; /* Firefox */
        -ms-user-select: none; /* Internet Explorer/Edge */
            user-select: none; /* Non-prefixed version, currently
                                  supported by Chrome and Opera */
}

<p>
  Selectable text.
</p>
<p class="noselect">
  Unselectable text.
</p>

Note that it's a non-standard feature (i.e. not a part of any specification). It is not guaranteed to work everywhere, and there might be differences in implementation among browsers and in the future browsers can drop support for it.

More information can be found in Mozilla Developer Network documentation.

Try this CSS code for cross-browser compatibility.

-webkit-user-select: none;
-khtml-user-select: none;
-moz-user-select: none;
-o-user-select: none;
user-select: none;