Are there any disadvantages to using AJAX?

Question

Are there any disadvantages to using AJAX?

Answer 1

Browser compatibility.

Answer 2

No integration with the browser's history.

Answer 3

Inability to update the client without "polling", which means querying the server every X seconds.

Answer 4

User may not know via the client that an AJAX operation was made, or if it failed. It can be difficult to recover from client side errors caused by a failed AJAX call.

Answer 5

Asynchronized access to data means it's harder to make things go correctly in every combination of actions.

Dependency of javascript makes the site unusable for some. Also javascript performance can be a bottleneck in resource limited environments.

Answer 6

If you build a site that requires Ajax to see content and perform tasks, you have several major problems. Ajax-only content/functions are invisible/unavailable to:

• search bots
• many mobiles
• people with Javascript turned off

etc etc.

However, if you build a site using the progressive enhancement principle, those problems are solved, and you still get to serve nice-to-use Ajax to most users.

Progressive enhancement involves first creating your site using bare-bones (X)HTML, on REST-like principles (at least to the extent of requiring POST requests for state changes). Simple semantic markup; forget about CSS and Javascript.

Step one is to get that right, and have your entire site (or as much of it as makes sense) working nicely this way for search bots and Lynx-like user agents.

Then add a visual layer: CSS/graphics/media for visual polish, but don't significantly change your original (X)HTML markup; allow the original text-only site to stay intact and functioning. Keep your markup clean!

Third is to add a behavioural layer: Javascript (Ajax). Offer things that make the experience faster, smoother, nicer for users/browsers with Ajax-capable JS... but only those users.

Answer 7

Makes it really Hard to do functional testing .

Answer 8

It requires javascript. And you have to admit to your friends how "Web 2.0" you are. Instead of being hard core old school: It's all tables for layout and frames for navigation for me.

Answer 9

Yes, Ajax is not supported by old browsers or browsers which don't have javascript enabled. Nowadays, most of the browsers do have support for Ajax -- even mobile browser like the one on the IPhone.

The biggest issue for me is that Ajax adds complexity to the project.

There are many ajax libraries out there, which are suppose to make life easier. In most cases, these libraries are easy to use to create a "Hello World" application. One of the main issues which is most of the times kept asside by Ajax libraries is (client-side) error handling/logging.

For larger projects, the developer has to understand the internals of the library, which adds a new learning discipline to the project.

Answer 10

Some of our big clients -for security reasons- took a corporate decision of having javascript switched off. Therefore no AJAX is possible.

If you are going to develop something using AJAX for a given client be sure that your client are allowed to use javascript.

Restrict your application to a reasonable number of browsers and browsers versions.

Crossbrowser compatibility can make your life miserable.

Answer 11

Ultimately, the problem is that it introduces is complexity. Most problems inherent with AJAX sites (bookmarking, browser history, graceful degradation, etc...) can be overcome with a good design, so there are not really any disadvantages to a well designed AJAX enabled site. The problem is a creating such a site requires a lot of design and very good developers who can manage the complexity.