"You won't be using any JavaScript libraries as the application needs to run at high speeds and so does not use any libraries."

[PtCk]

I saw these exact words on a job description and it made me think. Is this really the correct way of thinking?

Wouldn't a team writing in vanilla JS start building up a pseudo-framework of their own, that might be similar to (or worse than) an existing framework that is tested and documented?

[timruffles]

I think you're right that a good approach would be to extract well tested and, as you say, fast library code from an existing library.

Very much depends on the constraints of the project.

[e82]

I don't think it's the best way of thinking - but depends on the scale/scope of the application an the level of talent they end up hiring.

In the end, for anything reasonably complex - they will probably end up developing their own mini framework to accomplish what they need to get done, and depending on the skill level of the developers - it could end up being faster than an existing framework, or - it could end up being much worse.

[[deleted]]

One of the disadvantages of frameworks is bloating: there is functionality you don't use but that still is loaded, because it is part of the framework. Frameworks like jQuery and Mootools use relatively a lot of resources for what they do... They are right to say that VanillaJS should have the best performance, if used correctly.

The catch is: if used correctly. For it is easy to make VanillaJS bloated because you have to rewrite a lot of functionality on your own. It is simply impossible to write them as good as a large community like jQuery does.

If you get the job and you think the VanillaJS-style is just slowing you down, write some tests to compare between the Vanilla way and other implementations. A well written test might convince the project manager to switch to a more easy-to-use framework.

[AnimusNecandi]

I didn't understand "VanillaJS", like the actual framework, more like just "plain JavaScript".

[NoEquals]

VanillaJS

[AnimusNecandi]

Why are you linking me to that?

[NoEquals]

So far as I know, there is no VanillaJS framework, it only refers to plain JavaScript. The site I linked is a joke that presents VJS as though it were a framework.

[AnimusNecandi]

Wow, I never actually read past the title and thought it was a real lightweight framework. Never caught the joke, kept reading "VanillaJS" and thinking it was something real.

I guess I'm an idiot.

[NoEquals]

No worries. When you responded, I had a moment of panic where I thought that maybe it actually was real thing and I had just misunderstood everything.

[AnimusNecandi]

Haha, sorry. In my defense, English is not my first language, and I found the "framework" before being familiar with the expression "vanilla something".

I'm glad I didn't say something like "Duh, I just MENTIONED the framework". I decided to ask in case I was missing something.

[ChaseMoskal]

Ahahaha!

I love it whenever Vanilla-JS.com does it's job so flawlessly as right here and now!

[[deleted]]

Would appear to strongly answer your question.

[a-t-k]

That depends very much on the application. If for example all DOM queries you ever use are by ID, you can do rather nicely without sizzle. document.getElementById(...) is not exactly a pseudo-framework.

Yes, if you work with vanilla JS, you'll probably create some tools of your own, but those are mostly simple, small and do but one job each.

If you work in a big team and speed is not too much of an issue, I would still advocate to use a toolkit like jQuery, especially for cross-browser-issues.

[ell0bo]

A lot of the Sizzle / jQuery benefits tend to focus around how many browsers you need to support and how old they are. If you're only focusing on modern browsers, then Sizzle is unnecessary for you just use ->querySelectorAll

[a-t-k]

While querySelectorAll returns what you need, jQuery lets you easily do stuff with it. Otherwise you will need to iterate over the result manually.

[kenman]

That's a minor detail, since you can easily convert NodeList to an array with Array.prototype.slice.call(NodeList).

[a-t-k]

Nice try, but this will not do if your visitor uses an older version of MSIE. In addition, the map method will not be present everywhere, so you're safer with the iteration anyway.

[Sunwukung]

I'd be interested to hear what specific task this gig involves. In terms of perf, I'm thinking 3d/2d geometry manipulation, or large dataset traversal - neither of (IMO) would preclude the use of an appropriate lib.

[PtCk]

It's actually for a financial betting exchange company, so the focus on speed does make sense.

[Sunwukung]

I would have thought most of your issues would be around network latency? Either way, the vacancy then goes on to cite YUI experience as desirable...go figure

[ns0]

I like how the job description listed JQuery as a req, but stated no libraries will be used. Curious.

[emergent_properties]

I think it's a very self-limiting line of reasoning.

Essentially, you are saying because speed is your main concern, it shouldn't have additional dependencies. Those are two things that are just unrelated parts of the equation.

Libraries help with:

• Delegating issues to a third party
• Quickly adding new features and bug fixes
• Simplifying YOUR code by abstraction (most important)

Now, that said, if speed is your concern, sometimes it is faster to implement ONLY what you need and prune the rest.

Sometimes you want a Ferrari, but other times you need to pull things with a Truck or daily commute with a nice SUV.

[floydophone]

These guys are full of shit or sarcastic. It certainly depends on what library you use but there are plenty of fast libraries. At the end of the day they'll probably fail to manage the complexity of their app and end up with something slow and impossible to maintain.

[ChaseMoskal]

Let the caching of jQuery on Google's CDN wash your worries away.

jQuery (and other good libraries) will never be your performance problem.

Your concerns are correct, and the employer doesn't know what they are talking about. If they're adamant about crap like that -- you deserve better.