客户端或服务器端处理？

Question

So, I'm new to dynamic web design (my sites have been mostly static with some PHP), and I'm trying to learn the latest technologies in web development (which seems to be AJAX), and I was wondering, if you're transferring a lot of data, is it better to construct the page on the server and "push" it to the user, or is it better to "pull" the data needed and create the HTML around it on the clientside using JavaScript?

More specifically, I'm using CodeIgniter as my PHP framework, and jQuery for JavaScript, and if I wanted to display a table of data to the user (dynamically), would it be better to format the HTML using CodeIgniter (create the tables, add CSS classes to elements, etc..), or would it be better to just serve the raw data using JSON and then build it into a table with jQuery? My intuition says to do it clientside, as it would save bandwidth and the page would probably load quicker with the new JavaScript optimizations all these browsers have now, however, then the site would break for someone not using JavaScript...

Thanks for the help

Answer 1

Congratulations for moving to dynamic sites! I would say the following conditions have to be met for you to do client-side layout (it goes without saying that you should always be doing things like filtering DB queries and controlling access rights server side):

• Client browser and connection capabilities are up to snuff for the vast majority of use cases
• SEO and mobile/legacy browser degradation are not a big concern (much easier when you synthesize HTML server side)

Even then, doing client-side layout makes testing a lot harder. It also produces rather troublesome synchronization issues. With an AJAX site that loads partials, if part of the page screws up, you might never know, but with regular server-side composition, the entire page is reloaded on every request. It also adds additional challenges to error/timeout handling, session/cookie handling, caching, and navigation (browser back/forward).

Finally, it's a bit harder to produce perma-URLs in case someone wants to share a link with their friends or bookmark a link for themselves. I go over a workaround in my blog post here , or you can have a prominent "permalink" button that displays a dynamically rendered permalink.

Overall, especially when starting out, I would say go with the more kosher, better supported, more tutorialed, traditional approach of putting together the HTML server side. Then dip in some AJAX here and there (maybe start out with form validation or auto-completion), and then move on up.

Good luck!

Answer 2

It is much better to do the heavy lifting on the server side.

In CodeIgniter you create a view, looping through all the rows in the table adding in the classes or whatever else you would need. There is no reason at all to do this in Javascript.

Javascript is a sickly abused language with unfortunate syntax. Why on earth would you want to load a page, and then issue a AJAX call to load up some JSON objects to push into a table is beyond me. There is little reason to do that.

Javascript (and jQuery) is for end user enhancement. Make things slide, flash, disappear! It is not for data processing in even the mildest of loads. The end user experience would be crap because you're relying on their machine to process all the data when you have a server that is infinitely more capable and even designed for this specifically .

Answer 3

It's better to do as much as possible on the server-side because 1) you don't know if the client will even have JavaScript enabled and 2) you don't know how fast the client-side processing will be. If they have a slow computer and you make them process the entire site, they're going to get pretty ticked off. JavaScript/jQuery is only supposed to be used to enhance your site, not process it.

Answer 4

You got the trade-off correctly. However, keep in mind that you can activate compression in the server side, which will probably make adding repetitive markup to format the table a small bandwidth cost.

Keep also in mind that writing Javascript that works in all browsers (including hand-helds) is more complicated than doing the same server side in PHP. And don't forget that the "new JavaScript optimizations" do not apply to the same extent to browsers of handheld devices.

Answer 5

It depends on your target market and the goal of your site.

I strongly believe in using the client side where ever you can to offload work from the server. Obviously its important you do it correctly so it remains fast for the end user.

On sites where no-js support is important (public websites, etc), you can have fallbacks to the server. You end up doubling code in these situations but the gains are very beneficial.

For advanced web applications, you can decided if making JS a requirement is worth the trade of losing a (very) few users. For me, if I have some control over the target market, I make it a requirement and move on. It almost never makes sense to spend a ton of time to support a small percentage of potential audience. (Unless the time is spent on accessibility which is different, and VERY important regardless of how many people fit into this group on your site.)

The important thing to remember, is touch the DOM as little as possible to get the job done. This often means building up an HTML string and using a single append action to add it to the page vs looping through a large table and adding one row at a time.

Answer 6

I do a great deal of AJAX app development and I can tell you this from my experience. a good balance between the two is key.

do the raw data server-side but use javascript to make any modifications that you would need to it. such as paging, column sorting, row striping, etc.

I absolutely love doing everything in AJAX heh.. but there are some short falls to doing it using AJAX, and that's SEO. search engines do not read javascript, so for the sake of your website's page rank, I would say have all data served up server side and then formatted and made look cool client-side.

The reason I love AJAX so much is because it drastically speeds up your APP usage by the user as it only loads the data you need to load where you need to load it, versus load the entire page every time you do something... you can do a whole bunch of stuff, such as hide/show rows/columns (we are talking about table manipulation here because you mentioned a table) and even with these show/hide actions add delete actions where when you click a delete row or button it deletes that row not only visually but in the database all done via AJAX calls to server-side code.

in short.

raw data: server-side sending to the client the raw data in html layout (tables for table structured data, however I do everything else in divs and other flexible html tags, only do tables for column/row style data)

data formatting: client-side which also includes any means of interacting with the data. adding to it, deleting from it, sorting it differently etc. This achieves two things. SEO, and User Experience (UX).