JS Array traversal

JS array The general situation can be traversed in the following ways:

<script type= "Text/javascript" >//such as Var values=new Array (); values[0]= "Beijing"; values[1]= "Tianjin";//other omit//traverse 1for ( var i=0;i<values.length;i++) {alert (values[i]);} Traverse 2for (var ele in values) {alert (Values[ele]);//Subscript}</script>

However, for-in cannot be used in a random situation, the following problems occur:

<script type= "Text/javascript" >var data=[{name: "A", Age:12},{name: "B", Age:11},{name: "C", Age:13},{name: "D", AGE:14}];  for (var o in data) {     alert ("Text:" +data[o].name+ "value:" +data[o].age);   } </script>

The result is not popped four times, but popped eight times, and the other four times are undefined