jQuery General Performance Tips

• use the latest jQuery
• Caching Selections (assign it to a variable) 
• Caching Other Items
• Use element properties (DOM) when possible (instead of jQuery properties)

jQuery Type Testing Functions

• Determine the type of an object
• Useful for optional parameters & validation

Functions:

• $.isArray(array)
• $.isFunction(function) - another way to do this ( if (typeof <functionName> == "function")
• $.isEmptyObject(object)
• $.isPlainObject(object)
• $.isXmlDoc(doc)
• $.isNumeric(number)
• $.isWindow(window)
• $.type(object)

 Return Values:

• boolean
• number
• string
• function
• array
• date
• regexp
• object
• undefined
• null

Turn javascript object into a string

use json2.js from http://www.JSON.org/json2.js

e.g.
<script src="json2.js"></script>
...
JSON.stringify( {
    FirstName: $('#FirstName').val(),
    LastName: $('#LastName').val()
});

To turn a JSON string into javascript ojbect, use parseJSON.

var json = '{"fname" : "john", "lname" : "smith", "age" : 35}';
var jsObject = $.parseJSON(json);

Ways to display XML data on browser

• Open the xml file from IE
• Open XML file from IE using XSL
• Use jQuery to load the whole XML file into a container
• Use jQuery to parse the XML file into a container
• Display the XML file (with/without XSL) in an iframe tag of the HTML file

       e.g. <iframe src="test.xml" scrolling="no" frameborder="0"></iframe>