javascript禁制后退键(Backspace)实例代码

代码如下:function banBackSpace(e) {                  var ev = e || window.event;//获取event对象                  var obj = ev.target || ev.srcElement;//获取事件源                  var t = obj.type || obj.getAttribute(‘type’);//获取事件源类型                  //获取作为判断条件的事件类型                  var vReadOnly = obj.readOnly