Navigating a JSON object in Javascript

Fri, Jun 26, 2009

Tech Tips

The Scenario:
You are working with a web service that returns JSON. You’ve used your javascript library to convert the string into a JSON object. Now you need to access the data in the object using javascript. Here are some examples:

JSON Property Types
The properties of a JSON object are going to be of the following types: another Object or an Array of Objects. Objects are name – value pairs. The value that is returned can be a string, a number, another object, an array, true, false, or null.

Accessing an Object type in JSON:

//A Simple Example:
// Your JSON object(yourData) has a name property, 
//  you could get it this way:
var name = yourData.Name;
// alternatively you can use a string index:
var name = yourData["Name"];

//A Nested Example
// Your JSON object(yourData) has a Books object 
//  with nested Book objects
var books = yourData.Books;
for (var x in books) 
{
 var book = books[x];
 var title = book.title;
}

Accessing an Array type in JSON:

//A Nested Example with an Array
// Your JSON object(yourData) has a 
// Books array with nested Book objects
var books = yourData.Books;
for (var x = 0; x++; x< books.length) 
{
 var book = books[x];
 var title = book.title;
}

Getting Property Names

// When you want to know the name of the 
//  properties of an object you can iterate 
//  through the object using for - in loop
var books = yourData.Books;
for (var x in books) 
{
 alert(x);
}
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