Using this method allows for complex form validation while the user is filling out the form in stead of and in addition to validation following submission. This means that a user can enter their ZIP code for their shipping address and see the shipping charges added to the form before they move on or they can see that the username they want is already taken and have some suggestions shown to them as they type.
The idea is that we can add some of the responsiveness of a desktop application to a web page, reducing the latency that makes filling out forms and waiting for responses so tedious on the web. This can lead to more users completing their tasks as well as a greater sense of satisfaction with the experience among users.
Potential Problems with using Ajax
From our ideal of failing gracefully we move to the concept of progressive enhancement. Progressive enhancement with Ajax means designing a web site or application that functions without Ajax and then making it easier to use for users with shiny new browsers that support the required technologies.
Following the model of progressive enhancement when adding the new functionality to the web site will continue to uphold the ideal of access to information and functionality for all visitors. This will result in an accessible web site that functions well for everyone regardless of their abilities or their browsers abilities. It’s not about holding back progress as it is making sure nobody is left behind as we go forward.