Traversing in JSON Data

Question

I have a JSON data as shown below, I want to traverse into it with loop, but data.length is returning 1 while it should return 2.

Please help me out how can I traverse into data with loop without modifying it

 

var data=[{

"468040": {

"Author": "William von Hagen",

"Title": "Ubuntu Linux Bible"

},

"541115": {

"Author": "Lohith G.N.",

"Title": "Windows Phone 7.5 Application Development with F#"

}

}]

alert(data.length);  //returning 1 instead of 2