IE 8 beta 2 Ajax Features

Sunava Dutta has detailed the enhancements made to IE 8 beta 2 for Ajax developers including XDR, XDM/postMessage, DOM Storage, offline detection, and more...

XDomainRequest(XDR)

This is an object built from the ground up to make client-side cross-domain calls secure and easy. To reduce the chances of inadvertent cross domain access, this object requires an explicit acknowledgement for allowing cross domain calls from the client script and the server.

Additionally, it reduces the need for sites having to resort to the dangerous practice of merge scripting from third parties directly into the mashup page. This practice is dangerous because it provides third parties full access to the DOM. All this comes with the added benefit of improved client-side performance and lower server maintenance costs thanks to the absence of a need for server farms for proxying.

DOM Storage

The W3C’s HTML 5 DOM Storage objects provide a much simpler global and session storage model for key/value pair string data. Sites can store data for the life of a tab or until the site or user clears the data.

Updates for Beta 2 include changing the name of the persistent globalStorage attribute to localStorage and the removal of the need to specify the domain when writing to the localStorage.

 

XMLHttpRequest

Introducing the XDomainRequest object in IE8 hasn’t diverted our attentions from constantly tweaking and improving XMLHttpRequest, which will continue to be our flagship object for same-domain communications.

Post-Beta 1 energies here have focused on a few bug fixes around reliability and working with the Web Apps Working Group to clarify and improve the draft specification, our compliance with it, and W3C public test cases.

 

ToStaticHTML, to JSON, and fromJSON

In addition, IE8 Beta 2’s toJSON and fromJSON methods provide improved performance as opposed to non-native Javascript deserializers and serializers. Our implementation is based on the ECMAScript 3.1 proposal for native JSON-handling which uses Douglas Crockford’s API.

In addition to the performance benefits of going native, the JSON parser provides a safe alternative to the eval() method, which has been a common and dangerous way to revive JSON objects, and could allow arbitrary script functions to execute.