chrome浏览器解除网页右键屏蔽

javascript:(function() { 
    function R(a){
        ona = "on"+a; if(window.addEventListener) window.addEventListener(a, function (e) { 
            for(var n=e.originalTarget; 
            n; 
            n=n.parentNode) n[ona]=null; 
            }, true); 
        window[ona]=null; 
        document[ona]=null; 
       if(document.body) document.body[ona]=null; 
       } 
R("contextmenu"); 
R("click"); 
R("mousedown"); 
R("mouseup"); 
R("selectstart");
})()