Не вредит ли сайту код/скрипт?

Кто знает что это за код, и навредит ли этот код сайту и ПС? :)

document.oncontextmenu = cmenu; function cmenu() { return false; }
function test(form){
alert(form.value);
}
function preventSelection(element){
var preventSelection = false;

function addHandler(element, event, handler){
if (element.attachEvent)
element.attachEvent('on' + event, handler);
else
if (element.addEventListener)
element.addEventListener(event, handler, false);
}
function removeSelection(){
if (window.getSelection) { window.getSelection().removeAllRanges(); }
else if (document.selection && document.selection.clear)
document.selection.clear();
}
function killCtrlA(event){
var event = event || window.event;
var sender = event.target || event.srcElement;

if (sender.tagName.match(/INPUT|TEXTAREA/i))
return;

var key = event.keyCode || event.which;
if (event.ctrlKey && key == 'A'.charCodeAt(0))
{
removeSelection();

if (event.preventDefault)
event.preventDefault();
else
event.returnValue = false;
}
}
addHandler(element, 'mousemove', function(){
if(preventSelection)
removeSelection();
});
addHandler(element, 'mousedown', function(event){
var event = event || window.event;
var sender = event.target || event.srcElement;
preventSelection = !sender.tagName.match(/INPUT|TEXTAREA/i);
});

addHandler(element, 'mouseup', function(){
if (preventSelection)
removeSelection();
preventSelection = false;
});

addHandler(element, 'keydown', killCtrlA);
addHandler(element, 'keyup', killCtrlA);
}
preventSelection(document);