JavaScript禁用鼠标右击

 (function(){
        var doc=document,
          ua = navigator.userAgent.toLowerCase(),
          check = function(r){return r.test(ua);},
          isOpera = check(/opera/),
          isChrome = check(/chrome/),
          isWebKit = check(/webkit/),
          isSafari = !isChrome && check(/safari/),
          isSafari2 = isSafari && check(/applewebkit\/4/),
          isSafari3 = isSafari && check(/version\/3/),
          isSafari4 = isSafari && check(/version\/4/),
          isIE = !isOpera && check(/msie/),
          isIE7 = isIE && check(/msie 7/),
          isIE8 = isIE && check(/msie 8/),
          isIE9 = isIE && check(/msie 9/),
          isIE10 = isIE && check(/msie 10/),
          isIE11 = isIE && check(/msie 11/),
          isIE6 = isIE && !isIE7 && !isIE8 && !isIE9 && !isIE10 && !isIE11,
          isGecko = !isWebKit && check(/gecko/),
          isGecko2 = isGecko && check(/rv:1\.8/),
          isGecko3 = isGecko && check(/rv:1\.9/);
        function preventKey(e) {
          var ev = e || window.event,//获取event对象
            obj = ev.target || ev.srcElement,//获取事件源
            t = obj.type || obj.getAttribute('type'),readonly = obj.readOnly||obj.getAttribute('readonly'), code = ev.keyCode||ev.which||ev.charCode,charcode = String.fromCharCode(code).toLowerCase();//获取事件源控件类型,控件只读属性，键盘值
          if ( (code == 8 && t != "password" && t != "text" && t != "textarea")||(readonly&&(t == "password" || t == "text" || t == "textarea"))) {//除不只读输入框外禁止后退键
            return false;
          }
          if (((isOpera || isGecko)?ev.which==0:true)&&(code == 116 || code == 122|| code == 123 || (ev.shiftKey && code == 121))||(((isOpera || isGecko)?ev.which!=0:true)&&ev.ctrlKey && (charcode == 'a' || charcode == 's'))) {//屏蔽 F5,F11,F12,shift+F10,ctrl+a,ctrl+s
            if (isIE)
              ev.keyCode = 0;
            ev.returnValue = false;
            return false;
          }
        };
        if (isOpera || isGecko)
          doc.onkeypress = preventKey;
        else if (isIE || isChrome || isSafari)
          doc.onkeydown = preventKey;
        if(isIE)document.onselectstart=function(){return false;};
        doc.oncontextmenu = function(){
          if(window.event){
            window.event.cancelBubble = true;
            window.event.returnValue=false;
          }
          return false;
        };
        try{window.history.forward(1);}catch(e){}
      })();