JS检查当图片不存在时显示默认图片和键盘大小写键状态

当图片不存在时显示默认图片

 <script type="text/javascript">
         var imgs = document.images;
         for(var i = 0;i < imgs.length;i++){
             imgs[i].onerror = function(){
                 this.src = "http://images2015.cnblogs.com/blog/66516/201511/66516-20151104233425055-1712623285.png";
             }
         }
 </script>

或者：

 <img src="" border="0" onerror="this.src=' http://images2015.cnblogs.com/blog/66516/201511/66516-20151104233425055-1712623285.png'"/>

键盘大小写键状态

 <script type="text/javascript">
             function detectCapsLock(event) {
                 var e = event || window.event;
                 var o = e.target || e.srcElement;
                 var oTip = o.nextSibling;
                 var keyCode = e.keyCode || e.which; // 按键的keyCode
                 var isShift = e.shiftKey || (keyCode == 16) || false; // shift键是否按住
                 if (
                     ((keyCode >= 65 && keyCode <= 90) && !isShift) // Caps Lock 打开，且没有按住shift键
                     || ((keyCode >= 97 && keyCode <= 122) && isShift)// Caps Lock 打开，且按住shift键
                 ) {
                     oTip.style.display = '';
                 }
                 else {
                     oTip.style.display = 'none';
                 }
             }

             window.onload = function () {
                 document.getElementById('<%= txtUserName.ClientID %>').focus();
                 document.getElementById('<%= txtPassword.ClientID %>').onkeypress = detectCapsLock;
             };
 </script>