js禁止鼠标右键及禁止F12查看源代码

F12审查元素的情况下，可以随机更改代码，注入恶意JS等等，避免这种情况如下：

一、屏蔽F12 审查元素

<script>
    document.onkeydown = function () {
        if (window.event && window.event.keyCode == 123) {
            alert("F12被禁用");
            event.keyCode = 0;
            event.returnValue = false;
        }
        if (window.event && window.event.keyCode == 13) {
            window.event.keyCode = 505;
        }
        if (window.event && window.event.keyCode == 8) {
            alert(str + "\n请使用Del键进行字符的删除操作！");
            window.event.returnValue = false;
        }
    }

二、屏蔽右键菜单

 document.oncontextmenu = function (event) {
        if (window.event) {
            event = window.event;
        }
        try {
            var the = event.srcElement;
            if (!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
                return false;
            }
            return true;
        } catch (e) {
            return false;
        }
}

三、屏蔽粘贴

document.onpaste = function (event) {
        if (window.event) {
            event = window.event;
        }
        try {
            var the = event.srcElement;
            if (!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
                return false;
            }
            return true;
        } catch (e) {
            return false;
        }
    }

四、屏蔽复制

document.oncopy = function (event) {
     if (window.event) {
         event = window.event;
     }
     try {
         var the = event.srcElement;
         if (!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
             return false;
         }
         return true;
     } catch (e) {
         return false;
     }
 }

五、屏蔽剪切

document.oncut = function (event) {
       if (window.event) {
           event = window.event;
       }
       try {
           var the = event.srcElement;
           if (!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
               return false;
           }
           return true;
       } catch (e) {
           return false;
       }
   }

六、屏蔽选中

document.onselectstart = function (event) {
       if (window.event) {
           event = window.event;
       }
       try {
           var the = event.srcElement;
           if (!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
               return false;
           }
           return true;
       } catch (e) {
           return false;
       }
   }