I have a site written in Asp webforms. It uses ajax heavily.

Most forms on the site are submited with javascript. Javascript validates the input and sends it to /ajax.ashx on the server. The server processes the request and sends back a JSON response. My javascript uses the JSON to create html, which it inserts into the Dom.

I'm making a new version of my website written using asp MVC3. I've been looking at tutorials on this subject, and some of them remend doing ajax in a different way. Rather than sending data and then building + inserting html with javascript, they create html at the server, and use javascript only to insert it into the Dom. For instance, in this tutorial.

Which way should I use? Using the new method will be quicker, but is it better?

I have a site written in Asp webforms. It uses ajax heavily.

Most forms on the site are submited with javascript. Javascript validates the input and sends it to /ajax.ashx on the server. The server processes the request and sends back a JSON response. My javascript uses the JSON to create html, which it inserts into the Dom.

I'm making a new version of my website written using asp MVC3. I've been looking at tutorials on this subject, and some of them remend doing ajax in a different way. Rather than sending data and then building + inserting html with javascript, they create html at the server, and use javascript only to insert it into the Dom. For instance, in this tutorial.

Which way should I use? Using the new method will be quicker, but is it better?

• javascript
• ajax
• asp-mvc

5 Answers 5

That's a subjective question. Both approaches are possible and there is no better way. There are pros and cons of each approach.

Building the HTML on the server is easier and will require you less efforts but consumes more bandwidth pared to the first approach.

If you decide to go the first way you could use some client side templating framework which might help you simplify the generation of DOM elements on the client.

Creating html code directly into the server and injecting it with an ajax call is very fast and simple, the real problem is that in that way your service is bound to be used with that specific application. By sending RAW data you allow any app to use that data in any way, without bounding it to a specific application.

returning json feels more flexible to me; you can change what happens with your json response, like the layout it results in. If you return html you return data mixed with layout. This doesn't feel right to me.

I believe it is better to separate the layout from the actual data. That is why you should pass data between your scripts and not HTML. If you go about it sending HTML, consider that you would have to build valid HTML and CSS, which might not sound hard at first but then you'll start using CSS that is not loaded in the file calling the ajax, etc.

Always separate content (data) from layout. That's why there is HTML and CSS, to separate layout from data. So why mess things up by mingling HTML between data?

Building the html serverside will probably be faster and not bog down the client which is important. Rendering data into HTML with javascript takes time and not every browser is fast with js (i.e. older versions of IE) so things can slow down if you're doing a lot of this.

Like previous posters said, it's kinda subjective because it depends on how much you're offloading to the client. I'm of the opinion that if you can do things serverside, you should.

If you are going to be using this service to return JSON to other applications/clients, then it's probably a good idea to just leave it as JSON and let the client do what it needs on their side.