javascript数组输出的两种方式

<script language="javascript" type="text/javascript">
var str = "how are you today";
var arr = str.split(" ");
for(var key in arr){
 document.writeln(arr[key]);
}
</script>

<script language="javascript" type="text/javascript">
var str = "how are you today";
var arr = str.split(" ");
for(var i=0;i<arr.length;i++){
 document.writeln(arr[i]);
}
</script>