Disable selection on document

script.js

/**
 * Disable selection on document
 */

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)) // 'A'.charCodeAt(0) можно заменить на 65
        {
            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);
}