Comments on: LABjs: why not just concat?

By: Dan

Dan — Mon, 07 May 2012 16:42:55 +0000

Surely the other benchmark you need to run here for the full picture is when caching is used. I notice that you’ve deliberately disabled caching in your requests to show the actual download time between a concatenated file and your load on demand. Interestingly, my results are sometimes longer for the labJS solution.

A more realistic scenario IMHO would be to compare any typical homepage which may have around 10 different JS files (eg. jquery, jquery UI, Knockout, modernizr, etc.etc) and illustrate that as one file vs many files when caching is optimised. I think you’ll see that for all but the first request, a single concat file will be quicker the more individual files are included. There are only so many that will load in parallel.

Where I think this way of loading really wins is only loading what you actually need. Personally, I’m less worried about how long a script takes to download (given I can optimise that) than I am about whether I actually need the script at all. There’s obviously no point spending time processing a script I’m not using. I quite like the fact that you can can customize many libraries, for instance jQuery UI lets you build a JS file containing only those parts of the UI you’re actually using on your site.

By: Kevin

Kevin — Tue, 10 May 2011 18:54:23 +0000

@Klevak

If you scroll to the beginning of the article, you’ll see this paragraph:

The short answer is, BOTH! You should concat files together when possible, and you should load your file(s) with a loader like LABjs. If you only do one or the other, you have missed out on the bigger picture of page-load optimization.

That way you reduce HTTP requests, and you prevent the single, large JS file from blocking the rendering of the page as it loads.

By: klevak

klevak — Thu, 28 Oct 2010 01:57:40 +0000

For developers with web sites that DO get over 160,000,000 page views a month, this post appears to concede that using LAB.js versus concatenating and minifying JavaScript into a single file adds little value. Considering that the majority of our visitors spend 10-15 minutes surfing our site, it’s it enough to rely on the browsers caching mechanisms? Am I missing something?

By: Filipe Martins

Filipe Martins — Tue, 07 Sep 2010 17:21:05 +0000

I’m not claiming that a 200ms or 1s delay isn’t noticeable. I’m saying that it probably won’t be important because it’s a one time only thing (don’t we love the cache?).
I do agree with you about the visual feedback, though.

By: getify

getify — Tue, 07 Sep 2010 12:06:45 +0000

“One second” was kind of an exaggeration. It’s been shown that users can perceive a delay if it’s over 200ms, which is quite possible if there’s a decent sized JavaScript file (or several) that need to be loaded when a user clicks a button. Of course, even a really small file could take 200ms if there’s high network latency involved. Because you can’t really guarantee someone’s connection speeds, I’d tend to assume loading files when a button is clicked could have a noticeable delay and would avoid it.

But certainly if you are going to do this, give some sort of visual indication (like a loader/spinner) even for the short loads (so that it’s present if the load is really long) so users aren’t multiple-clicking things because they click and don’t see a response quickly enough.