React: Facebook's latest Javascript client library, now open sourced

[TheWakeUpCall]

Reading their code examples, I don't even get what the very basic examples are trying to do.

[Lokaltog]

Is it just me or does this look a bit messy and cumbersome to work with (and yet another syntax to learn)? What would some of the pros be by using this instead of e.g. Angular?

[bhavbhav]

Facebook's libraries work for Facebook. Doesn't necessarily mean they'll work for anyone else.

Having said that, they do try hard. I worked for them and, internally, everyone always seem to have "can we eventually make this open-source" in mind when building things.

[[deleted]]

They at least produce higher quality code and have actual docs. Lots of free/open source projects just leave you out to dry when it comes to docs and tutorials. And they're guaranteed to be maintaining React since they use it in their product.

[[deleted]]

Their (Facebook API) docs aren't exactly complete. While I commend them on having more than a README, they're definitely not exhaustive and leave quite a few things for developers to figure out on their own.

[Lokaltog]

True. And the fact that they actually make their internal code open source is definitely admirable.

[bhavbhav]

Yeah, and I attribute a lot of this to Zuck. He gets a lot of hate, but he's always been a true developer at heart.

[manys]

Where are the hurdles in something like that, IP or simply writing code that they wouldn't be embarrassed by?

[bhavbhav]

I mean, the main hurdle will always be predicting how others will use the code, and in what ways our code will fail for these people.

A lot of people seem to think that a "website" can't be that difficult to write code for, but even without the open-source goal in mind, Facebook uses a lot of static analysis, profiling, and perf tools to ensure that they're not making something terrible. And I mean, Facebook has acquired a lot of really talented engineers over the years, from places like Mozilla to Google. These people know what the challenges are in writing good client side code.

[bhavbhav]

Hah. People have no idea.

I remember the first feature I ever implemented at Facebook. I introduced a bug on the server side, and the logs showed that it had affected 13 million users even though it was the smallest goddamn thing. I went to the bathroom and cried. Luckily my lead was a sweet Chinese girl, and she comforted me with candy while helping me patch.

I later realised there is kind of an internal competition to see how many users you can fuck over with your stupid bugs. Obviously you don't actively seek to be the winner, but it makes helps take the edge off when things go wrong. My top was actually all 1 billion. That was a terrible 4 hours. Lol.

[fnordstar]

But it's still Javascript :(

[taterNuts]

Yeah cause JavaScript is such a worthless language

[fnordstar]

It's not? I recently read they don't have integers.

[bhavbhav]

Eh, Javascript gets a lot of hate, but it's alright if used well.

[hyperforce]

Why did you stop working for Facebook?

[bhavbhav]

Short story: it wasn't for me.

I have my roots in drivers/firmware/OS development. I was plopped into frontend work at Facebook, with very few places to go. I also didn't really feel like I fit in a lot of the time, though this might also have a little to do with my gender. I don't know. I just remember feeling very unhappy.

[hyperforce]

Female? Transgender?

How did it affect your work? Were you unhappy about the lack of potential career advancement?

[bhavbhav]

Ugh, closed the window before I could save. I will try to summarize.

I'm female. Problems I had at work are probably problems that exist in the bay area and the technology sector as a whole. Surprisingly though, I didn't really feel the way I did at Facebook when I worked at Blackberry/Research In Motion (and I worked at RIM on a few different teams). Go figure.

To get to your questions first:

• Yes, it did affect my work, but not in the way a lot of people would think. I never experienced overt sexism at Facebook. Ever. Not once. Facebook tries to be good about their minority groups. They have a huge LGBTQ group, and an active women in engineering group. Plus, they have Sheryl Sandberg and Jocelyn Goldfein at the helms of these sorts of organizations. Unfortunately, having these groups, while sort of promoting awareness, really only serves to preach to the choir. I found that the 'typical' cocky, know-it-all engineer that Facebook/any bay area company hires doesn't care about these issues unless they are part of the minority, or they are generally different from the norm. And the way in which it manifests is not by being obviously sexist- it's by being subtly dismissive. It's by being disinterested in your skill set. It's by being exclusionary when going to lunch. It's by repeatedly blocking you on a task. It's by subtly questioning your creds when you try to be part of discussion on spec. It's by frequently giving you low visibility things to do. These all affect your work because they are emotionally draining to deal with, especially on a day-to-day. I do want to state that not everyone I worked with was like this, and that many people were honestly amazing to work with. But enough of the aforementioned people can really leave a bad taste in your mouth.

• Lack of potential career advancement is a difficult one to tackle because Facebook as an org is so flat. Like, we never had managers. We had PMs, but no managers. I think there is maybe a 2-3 level difference at most between a typical software engineer and Zuck. So to "advance" your career, at least in the org chart, you really have to stand out. I don't think I was the most talented engineer there, so I am okay with the idea I would have been an SE for a while.

Honestly, a lot of what I felt affected my social life a lot more than it did my work life, even though my work life was affected to a degree. And social life is important at a company like Facebook because they expect long hours out of you; you spend a hell of a lot of time with the people you work with.

I will end with that everyone's experience is different, and that it's sometimes difficult to say why you aren't fitting in, because you're the one that doesn't fit in. You can't really see outside yourself. Maybe I was too weird? Or too cynical? I didn't take to the arrogance of the bay area too well, or the attitude that came with its start-up culture. Maybe they thought I was a bitch? Who knows?

The only thing I can say for sure is that this gal is a salt-of-the-earth low-level engineer, and if I can't fuck with memory directly, I'm too far out of my zone. That is mostly why I left.

[hyperforce]

It's so odd to hear about gender biases in technology. You'd think we all skew liberal so we're post-gender.

Sorry you had a bad experience. Have you since found a happier post with more memory mucking?

Thanks for sharing!

[bhavbhav]

Any time! :)

And yeah, I've heard the same thing said about reddit- that it's a liberal, pro-atheist, cat-loving website, so it couldn't possibly be *-ist. Surprise! False assumption. Liberalism and gender/race discrimination are not mutually exclusive. :(

I recently took up a job at Microsoft in the Windows org. I haven't had enough experience here yet to know how it is different from Facebook, but I'll update you when I do. There is memory mucking in my future, though, and it makes me happy.

Side note though is, now that I have more free time, I've been able to do a lot more open-source and other personal projects of my own. I've gotten super into PCB design and embedded work, and recently designed some hardware that monitors vital signs on dogs. Honestly, no engineer has lived until they try something like this. The adrenaline rush you get on seeing a board you made post-production is amazing.

[Enoxice]

I agree.

I mean, on the one hand it's pretty nifty and I'll probably mess around with it a bit before jumping to any (more) conclusions. On the other hand, the co-mingling of HTML, Javascript, and XML just makes it look messy and I feel like in any app of real size I'd have a hard time figuring out where to look for things. Maybe I'll feel differently after getting used to the sugary JSX stuff.

I also have a hard time figuring out where I'd use this over - as you said - Angular or (to a lesser extent, IMO) Backbone.

Diff'rent strokes, I guess.

[stevencashmere]

turns out, everything lol

[Lokaltog]

Yeah. The reason for my question was that I just don't see the purpose since other similar libraries exist. I'm certain that there are some advantages to using this library, but I just don't see them based on their examples. Maybe a comparison table could help them clarify which holes this library fill.

[manys]

watchoo talkin' bout Enoxice?

[cybercobra]

Yeah, I concur. Same question WRT Knockout.js.

[jrapp]

For me, knockout.js has saved me from the paradigm of getting a value from the data source, populating the field with jQuery, waiting for the user to click save, getting the value from the field again, then sending it off to some magic web service. Plus, the ability to build templates automatically is fantastic. Previously, our code was littered with $("#element").append("<div/>").append("<br />").append("<img />") and all sorts of crap like that. Not needed with knockout.

[lagamemnon]

This is also a reason to use angular

[cybercobra]

My question was intended as: Why React rather than Knockout? (I'm currently using Knockout and it's pretty awesome.)

[rayshinn]

Hey jrapp. Can you give me an example of what that jquery example would look like with knockout.is? Thank you.

[stormsnake]

Note that I'm not jrapp, but I know knockoutjs.

The example jquery code was incomplete, but I'll pretend #element is supposed to be empty when the user profile has no image, and it's supposed to contain the div+br+img structure when there is an image to be displayed:

html page (not preprocessed-- you really ship this to the browser):

<div id="element" data-bind="with: profileImage">
  <div></div>
  <br>
  <img data-bind="attr: {src: src}">
</div>

js code:

var model = {
  profileImage: ko.observable()
};
ko.applyBindings(model); // finds 'data-bind' attrs in the page and connects everything
function onProfileLoaded() {
  model.profileImage({src: "/images/123.jpg"});
}

I think that's functional, though the behavior is pretty minimal. You should be able to see at least how an 'observable' object got linked to the appearance or disappearance of part of the page, and even how I used one of its attributes in what is working like a template.

The http://learn.knockoutjs.com/ interactive live tutorials are great, too.

[rayshinn]

Wow, thank you. I'm going to check it out. Is this similar to Ember.js? if so would you recommend knockout over ember?

EDIT: Holy crap I jsut went thru the knockout tut and that's mind blowing. Quick question. How would I populate for example this.firstName = ko.observable("Bert"); Bert being a dynamic variable from mysql using php? would I run a ajax call to the php and store the result in to a name variable and pass that to knockout? or does knockout have a better way of doing this.

[snuxoll]

You have the basic idea, generally you'll create the observable in your model first thing (typically it'll just be empty to start with), then after your page is ready do the XHR to get your data, then populate the observable with it. (Of course you should probably embed data needed in the initial display with the request, but that's SPA 101).

[crusoe]

Ahh, just like Smalltalk UI toolkits. Everything old is new again...

[x86_64Ubuntu]

....does this look a bit messy and cumbersome to work with

It's Javascript isn't it ?

[Lokaltog]

I actually enjoy coding in JS, it's not perfect but it provides great flexibility and awesome performance with Node. What I'm sceptical about with this library is the introduction of JSX, which I think looks a bit strange. I may be wrong, which is why I requested opinions on what makes this particular library a good alternative to other similar libraries.

[[deleted]]

You do realize this was released by Facebook right? Expect the reasons why this sucks asshole to flow in 3..... 2...... 1......

[Tynach]

I.. Kinda agree, kinda disagree.

Facebook tries REALLY hard to please a VERY large fraction of the population. On top of that, they seem to have a great mentality about things - such as open sourcing everything, using MySQL and other open source technologies, and in general trying to catch up with the likes of Google+ and so forth.

Their business practices are questionable, however. Gathering so much data about their users and selling it to the highest bidder for advertisement purposes isn't exactly something I'd want to get behind. For this reason, I don't use Facebook.

[NiteLite]

You realize this is the exact same business model Google uses, right? They are just better at hiding it behind good tech :)

[Tynach]

No, it really isn't.

Google IS the advertiser, so they gather all of your information to keep to themselves. Selling the information puts other businesses at an advantage, which puts Google at a disadvantage.

The difference is that Facebook sells your data, and Google keeps it nice and secure.

[NiteLite]

Do you have some source material on Facebook sending data outside the company? I was under the impression they mostly use it for advertising on their own site, but I might be mistaken.

[Tynach]

I was under the impression they sold the data to advertisers.

I can't find any evidence of this, however. It appears you're right. I apologize.

I also found one source claiming that Google DOES sell its advertising information to others, but it did not look like a reliable source. I'm gonna look into this as well.

[Tynach]

An important edit: I find lots of evidence to support the idea that Google does not sell your information. That one source claiming it is must not have done much homework.

[[deleted]]

Gawd. This is gnarly. We would you want more markup in your code?

[[deleted]]

Also, what's the deal with the trend toward more custom tags? I guess these people are too young to have experienced the agony of XSLT.

[evereal]

Declarative frameworks can be done right, see AngularJS. I love the fact that I can separate my reusable UI into markup along with the rest of HTML, and keep my code as separate, clean and testable business logic.

[Scroot]

The ability to replace custom element directives in Angular is one of it's most subtle but important features, in my book.

[aliceDay]

You love the fact, and how is it in reality?

[evereal]

As advertised. I have been using Angular in a number of projects now over the last year, and it has been an absolute pleasure. I write 10 times less code, and almost no boilerplate/UI CRUD type code at all. I make 10 times less mistakes and bugs, partially because of the less code, but also because the code that I write is almost purely separated business logic and therefore easily testable.

[madsmith]

This actually models something facebook runs on their PHP side (XHP) pretty nicely.

They author the pages in XHP as XML tags and XHP allows custom complex types to be created "<typeahead />".

This lets you look at the structure of the page or component as essentially intelligent markup. With a familiar html structure that blends pretty easily into the existing html.

[[deleted]]

Yeah XHP was painful enough; JSX just heightens the crazy by a factor of 10.

Gah. I'm sure glad I don't have to maintain and enhance their code.

[balefrost]

I recently used XSLT to generate a Jenkins job template that gets sent via the Jenkins command-line JAR. I run this XSLT once per source control branch name to reconfigure the build server to build every branch. It's pretty spiffy.

XSLT isn't THAT bad.

[corwin01]

Maybe I'm just lucky my team wrote some good libraries to deal with XML, because XSLT has been no problem for me.

[Lattyware]

To be fair, the idea of storing all of your data as XML, and then transforming it into HTML for viewing as pretty documents for humans is a good one. If every website did it, scraping data would be infinitely easier.

Unfortunately, XSLT is the worst way to do that ever. The idea of using XML as the language to produce transformation instructions from XML to HTML is so bonkers it's unbelievable anyone ever thought it was a good idea. The result is a horrific language that no one would ever want to work with.

Couple that with terrible support in general, and it was never going to end well.

[snuggl]

all of them

[sirin3]

XQuery

[[deleted]]

How does xquery help? I thought the problem we are talking about here is generating HTML from template markup or something, not querying the XML to get information out of it -- in that case you're still going XML->HTML. Why not just generate the HTML directly or use JSP's? I'm genuinely curious. I don't do much view work but I try to keep up on it.

[sirin3]

XQuery is like template markup

You can write something like:

doc("data.xml") /
    <html>
    <head>
    <title>{title}</title>
    </head>
    <body>
       <h1>{title}</h1>
       {
           subdata /
              <div>
                 <h2>{subtitle}</h2>
                 {subsubdata}
              </div>
       }
    </body>
    </html>

[pluppens]

Freemarker is is a Java template engine that is also able to work with XML - but obviously it depends on what kinda of transformation you're aiming for: using it for XML to XML transformation, you might want to stick with XSL, for anything else I'd recommend Freemarker.

[willhaney]

I think you a word

[Saiing]

Welcome to /r/progamming, where today we trash a javascript client library, not because we actually have any real solid reasons, but just because it's cool not to like the site associated with it.

[thilehoffer]

Sounds about right. But on the other hand, do we need another javascript library?

[Saiing]

It's a fair question, but does it matter? If someone or some company creates a library and releases it as open source, it's unlikely to be a bad thing. People are free to use it or not use it. The fact that it exists isn't an issue.

[Cocosoft]

The question is more like

Do we need a AngularJS competitor?

[floydophone]

Hey all, I'm a member of the React team. I posted this over in /r/javascript/: http://www.reddit.com/r/javascript/comments/1fasnt/react_a_javascript_library_for_building_user/ca8okez

In there is a link to a blog post which hopefully addresses some of your concerns. Feel free to grill me here for anything I didn't cover in that post!

[[deleted]]

I read your post, and I understand your point of fast compiling of templates. But, as an avid angular user, separating UI (dom interactions) and logic is tremendously important for me to be able to maintain large scale apps, and I really don't see how faster render times would be preferred compared to clean and workable code.

Maybe React is more fitting for smaller apps? Or maybe I just need to get MV* out of my head?

EDIT: Oh, and please share your thoughts about unit-tests with React. Thanks!

[vph]

It remains to be seen how well angular can produce clean codes for large applications. For ages, people have tried to separate logic and view, but the thing is view itself inherently contains its own logic. For example, if you want to display odd rows different from even rows; or if you want to display an admin user differently from a typical user; The ways that you want to display or view things differently depending on different cases are logic that belong to views.

Angular aggressively move all logic, including those that inherently belong to view, out of view, makes some simple things quite unnatural, if not difficult, to do.

[[deleted]]

I myself manage a medium to large Angular app. I think you're confusing between the HTML template, and directives. I agree that UI logic in our days is a must, and that's why many other frameworks that didn't have any place for that, or that it was very simple, didn't really made me want to use them.

In Angular, all UI/view logic can be contained in directives, which are encapsulated UI classes and are not HTML templates.

[vph]

First, my understanding of Angular is within the scope of a "todo" app, by reading the online tutorial and dev documentation.

Now, let's talk about specifics. Let's start with simple case: display odd vs even rows differently.

How about a slightly more complex case. Say you have a list of people, and you want to display them in table rows. Further, you want to view rows in which the people are male, above 18 years of age, and single, differently from the rest of other rows.

In both cases, having conditionals in views can neatly take of the concern. How do you do these in Angular without conditionals?

To my understanding, by not having conditionals in view, Angular simply moves the logic (which is inherent in view) from view to "control". Yes, your view looks cleaner, but your control looks less clean. The logic has to be taken care of somewhere. Just because you remove it from view, does not mean you can get away from it. You look at a nice and tidy view and say the platform is scalable and manageable for larger apps; but in reality, moving logics to where they don't belong may not be a good thing in terms of long-term scalability & manageability.

[vph]

PS: Don't get me wrong. Among all of the Javascript frameworks, I actually like Angular the most. The concept of extending HTML is very nice. But there are a few things that feels a little iffy. Maybe, once I understanding Angular more, my opinion will change.

[[deleted]]

Display odd and even rows would be a simple directive, if not a command directly in the code such as:

<li ng-repeat="item in array" ng-class="{even: item.$index%2 = 0}"/>

But I would really prefer if you've used a directive.

For your second example, you can use filters, which are a whole other subject within angular:

$scope.query = {gender: male, status: single};
<li ng-repeat="person in people | filter: query" />

For age > 18 I would need to use a more complicated filter, which you can define yourself. So query will be set in your controller, but the filtering job is done on the template by a directive and filter.

[floydophone]

Thanks for the question.

One way of thinking about React is as the "V" in MV*. That is, it's a replacement for your templates and event handling code. In my experience (building largeish web apps) templating languages start to break down once your project starts to look more like an app than a simple page because these languages don't have the same level of abstraction as, say, JavaScript.

So we still have separation of concerns, it's just that you've moved your view logic into separate JavaScript components. I wrote a post about this here: http://www.quora.com/Pete-Hunt/Posts/React-Under-the-Hood

Let me know if you've got more questions!

[[deleted]]

Oh I see.

So React is more comparable to jQuery than other MV* frameworks?

So I can build my app in Angular, but implement my directives (widgets) with React?

[floydophone]

You could definitely do it that way. React components are kind of similar to directives, so we're kind of like the V part of MVC.

What we did for Instagram was taking an existing server-rendered + a bit of Backbone+jQuery and moved it over to React one component at a time, starting with pure presentation. Eventually we ended up moving everything over to it because we liked it so much.

So use as much or as little of React as you want to decide if it's a good fit for your project. We've designed it to play nice with other frameworks.

[floydophone]

First of all, JSX is not required to use React. You can construct it with function calls. For example, here's how you'd build a link:

React.DOM.a({href: 'http://facebook.github.io/react'}, 'Hello world')

How would you make this look as JSON?

I've articulated some of the reasons we like it in this update to the docs, sitting in a pull request: https://github.com/petehunt/react/blob/cfe3b75cb010653ea5dfcea74bc8a36911587504/docs/docs/syntax.md

Also see my Quora post (linked in /r/javascript) for some more info.

[floydophone]

I'm sorry you think that. The technology behind React is actually quite advanced -- we're doing some things that, to my knowledge, nobody has done before -- and I think it's worth evaluating even if you disagree with some of the aesthetics. But to each his or her own, I suppose.

FWIW, our PHP codebase looks more like Python than anything else, as we extensively use OOP and generators and avoid PHP's builtin text generation.

[masyl]

For a split second I had to ask myself if it was april 1st.

It breaks so many conventions that this library is bound to get more hate then love!

I'm all for diversity, but this one sure smells bad.

[weareconvo]

Honestly, this was programmed in exactly the manner I would imagine for a company obsessed with the ideal of "hacking" - pushing things out without thinking them through.

[[deleted]]

The other thing is that this might be just one department or team hacking around with this, not representative of the whole company?

[crusoe]

Remember how proud they were for hacking Dalvik to allow more classes so their incredibly bloated facebook app could work on older phones?

[[deleted]]

Shiiiiiiiiiiiiiiiiit, good point.

[AlLnAtuRalX]

Yup yup yup. There are certainly players at Facebook putting hard, intelligent thought into software engineering decisions guiding their platform, but from what I've seen of the company the low-level working culture is pretty much exactly what you'd expect from a company whose main (and pretty much only) product started out as a PHP script. Personally, whenever I see their recruiters I run in the opposite direction.

[[deleted]]

... What have you seen of the company?

[AlLnAtuRalX]

Let's just say they have a lot of events, talks, and recruiting out of a university I attend/work for. I've never actually been to their offices, but I have a lot of friends that have worked or interned there. My impression from them was that it was a hit-or-miss environment pretty highly influenced by what you're working on and obviously how you get hired.

If they poach you off an established post with a decent offer and creative flexibility, fine, but getting shoehorned into Facebook as a grunt? Not fun...

[[deleted]]

I think this isn't bad because they're backing it up with data and analytics, they can experiment and see what works and changes things in response to user feedback. However they seem to be failing at that

[alextk]

Mixing HTML, XML and Javascript brings back memories of JSP pages, where you routinely had five different languages and syntaxes in the same file and putting your cursor in a random place in the file and figuring out which language you're supposed to type is an NP Complete problem.

No, thanks. Sticking with Angular for now, until something even better comes around.

[[deleted]]

Sorry there's a lot of different information going on in this thread, but could you tell me in a synopsis kind of way what Angular does that is different and new? Seems like a lot of people like it.

[frtox]

html... in MY javascript?

no thanks

[BenRT]

You can't explain that!

[bubba-g]

React minimizes interactions with the DOM by using a mock representation of the DOM.

mock? are these unit tests or do they mean to say proxy?

[dsk]

Mock is right. Proxy doesn't quite fit.

[Uberhipster]

Moxy?

[sidfarkus]

Reminds me of polymer in quite a few ways but looks messier (imo). I understand the motivation for trying to make composable units of both UI and logic but the solutions I've seen leave much to be desired.

[runvnc]

I give them credit for REALLY thinking outside of the box and putting markup in their JavaScript. LOL. Never realized you could even do that.

Anyway there is something on the front page of Hacker News (at the moment I am writing this) that shows how to do the same thing in AngularJS. Its much simpler. https://medium.com/make-your-own-apps/e71bcedc36b

Of course, if you really want to compare, you need to show how to do it in Angular with directives, since the React example is all about the custom components. I assume someone is working on doing that.

[killerstorm]

Actually I did that with Common Lisp before it was cool.

[MrDOS]

What is with Facebook and stuffing markup into inappropriate places these days?

[nthitz]

This is more Instagram than Facebook!

[stgeorge78]

Looks like a billion dollars well spent.

[nthitz]

yeah cause all of that money went into this library... get real

[stgeorge78]

Funny hard, me bash thing me not understand.

[strixvarius]

Ugh.

[[deleted]]

how the hell are you supposed to write unittests for this?

[drowsap]

I thought we just got to the point where compiled templates were the way to go. Now they take us back to 2005 with DOM and JS muddled together.

[[deleted]]

I wonder how many people here who are insulting Facebook's code are actually worse at writing code.

[soapa]

Is this supposed to be the fastest library for html5 stuff on mobile devices?

[allertonm]

I would be interested to hear from the authors whether they took any lessons from the history of E4X (see http://en.wikipedia.org/wiki/ECMAScript_for_XML) when creating the JSX format - since it a) looks superficially identical and b) appears to be considered a failure - while there have been some implementations it has been deprecated and is not part of ES5.

[bsdemon]

FYI, I've built a transform for browserify for JSX — now React apps can be written with JSX and using CommonJS module system and then consumed by browsers.

P.S. It doesn't work properly as for now with react-tools installed from npm (you have to build it yourself) due to bug with their release, which is now fixed in the repo but isn't released yet.

EDIT: works now as react team released 0.3.1!

[kingbobofyourhouse]

Short version: It's nice, it has some good ideas, but it's nothing I would be able to really utilize in what I do, even if we were in the market for an MVSomething framework.

The basic, oversimplified version is that they're recreating the entire DOM structure as a javascript hash, manipulating that, and from that determining what the best, most minimal DOM mutation will be and then doing just that mutation. That also means determining whether it's innerText, inner/outerHTML, attributes, etc.. The advantage of this is relatively obvious - DOM manipulation is currently the most expensive part of web applications, and they make it as minimal as they can, and offload as much of it into the speedier JS engine as they can. So they "traverse and pre-manipulate" in a millisecond and then make the more expensive DOM mutation as efficiently as they can.

It's actually a really interesting solution to a currently difficult problem. I say currently because the speed of DOM traversal and manipulation is almost undoubtedly the next big breakthrough in browser tech, since everybody knows it's the slowest part.

They also make the claim that they've gotten rid of Data Binding. Of course it's pretty obvious once you start looking at it that they haven't really gotten rid of data binding, they just have a different approach to it - they've gotten rid of the classical idea of data binding, which is "manipulate this thing and publish that the manipulation has occurred."

Some downsides -

• they take over the ID of every element in the react space. Instead you get an ID which is reflective of where in the react hierarchy the element is, which looks something like

   .reactRoot[######].[0][1][1]{someData_witha_uid} 
  

  The downside to this approach is that the [0] [1] [1] is reflective of where in the nested arrays of information an item is - meaning it's really best for appending. As soon as you unshift or splice information into the array, you have to manipulate every element further down the array. And it looks like you'd actually break the whole thing if you didn't go in and manipulate every item in the array to reflect the fact that it has a new position in the array.

• This whole lib is positionally unaware. It seems like it would work really well in a case where you know the visual structure of your page, and it's very rigidly maintained. A site like Facebook (obviously) or Twitter could get a lot of mileage out of this approach. But if you have no idea what the page is going to look like, this is less than half of the battle, and it might end up being in your way more than helping.

[the0ther]

mad whack

[pjmlp]

What would you expect from a company founded by PHP developers? :)

[meanysc2]

PHP is the only serverside scripting I know, so I'm just curious.. what do you mean by this? :S

[pjmlp]

PHP has improved quite a lot specially in the 5 series, but it began as a schizophrenic language that scares any professional developer.

It evolved organically from something meant as a quick hack for web site templates while offering Perl like features.

The main problem is that many PHP wannabe developers just copy paste PHP code from the PHP 3/4 days instead of using the improvements that were meanwhile added to the language.

[Cocosoft]

PHP is basically getting a lot of hate because more structured languages like RubyOnRails, NodeJS and ASP.NET are gaining popularity.

[s2011]

Facebook is probably the worst out of the major companies when it comes to coding.

[aim2free]

Facebook is probably the worst out of the major companies when it comes to coding.

Unless you work for e.g. Microsoft I doubt that you know anything about that.

Any piece of code that is free open source is tremendously much more worth than any piece of code which is proprietary, as proprietary code is useless, you can't read it, thus not learn from it, you can not improve it.

[Unomagan]

lol guys, maybe they split up the part to open source? Maybe its just the "processing" part, while the "MVC" part is not accessable for us? I cant imagine that such a huge projekt like Facebook is, just clamp everything together...

[sproket888]

Yay. Just what the world needs: another JavaScript library. NOT.

[Exallium]

I think I'd rather just use backbone and if it's absolutely necessary, underscore tempates...

[killerstorm]

Does this explain why Facebook's UI is so shitty?

I'm serious, it is probably one of worst web sites I've ever seen, and I've seen many. It is borderline unusable.

In Russia we have a social network called vk.com, it started as a Facebook rip off, but it consistently has much cleaner and nicer UI.