Wie deaktiviere ich die Textauswahl in HTML?

.unselectable {
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

<label class="unselectable">Unselectable label</label>

<label onselectstart="return false;">Unselectable label</label>

var labels = document.getElementsByTagName('label');
for (var i = 0; i < labels.length; i++) {
    disableSelection(labels[i]);
}
 
function disableSelection(element) {
    if (typeof element.onselectstart != 'undefined') {
        element.onselectstart = function() { return false; };
    } else if (typeof element.style.MozUserSelect != 'undefined') {
        element.style.MozUserSelect = 'none';
    } else {
        element.onmousedown = function() { return false; };
    }
}

<label>Try to select this</label>

<script>
    $.fn.extend({ 
        disableSelection: function() { 
            this.each(function() { 
                if (typeof this.onselectstart != 'undefined') {
                    this.onselectstart = function() { return false; };
                } else if (typeof this.style.MozUserSelect != 'undefined') {
                    this.style.MozUserSelect = 'none';
                } else {
                    this.onmousedown = function() { return false; };
                }
            }); 
        } 
    });

    $(document).ready(function() {
        $('label').disableSelection();            
    });
</script>