Node js - Bundler for http2
Question
I'm currently using babel to transform es6 code to es5 and browserify to bundle it to use it in the browser. Now I've began to using a http2 server (Nginx).
Http2 is more effective when it can load multiple small files instead of one big bundle.
How to best serve multiple js files instead of one big bundle?
2 answers
solution1
1 2016-03-16 11:43:28
I know that SystemJS can load multiple files in development without bundling, and for production you can use a DepCache to define the dependence trees of the modules you are importing
https://github.com/systemjs/systemjs/blob/master/docs/production-workflows.md
This approach would require you to ditch browserfy and change to systemjs as it only uses bundles.
solution2
1 2016-03-16 23:16:18
I see that you didn't get the answer on your question till now. Thus I try to help you in spite of HTTP/2 is new for me too (it explains the long text of my answer :-)).
Good information about HTTP/2 can be find on the page https://blog.cloudflare.com/http-2-for-web-developers/ . I repeat shortly:
- stop concatenating files
- stop inlining assets
- stop sharding domains
- continue minimizing of CSS/JavaScript files
- continue loading from CDNs
- continue DNS prefetching via
<link rel='dns-prefetch' href='...' />included in<head> - ...
I want to add two additional points about the importance of setting HTTP headers Cache-Control and Link :
- think about setting
Cache-ControlHTTP headers (especiallymax-age,expiresandetag) on all content of your page. See details below. I strictly recommend to read the Caching Tutorial . - set
LinkHTTP header to use SERVER PUSH of HTTP/2.
The setting of HTTP headers LINK: are important to use server push feature of HTTP/2 (see here , here ). RFC5988 and Section 19.6.1.2 of RFC2068 describe the feature existing in HTTP 1.1 already. Everybody knows Content-Type: application/json , but in the same way one could set less known Link: <...>; rel=prefetch Link: <...>; rel=prefetch , described here . For example, one can use
Link: </app/script.js>; rel=preload; as=script
Link: </fonts/font.woff>; rel=preload; as=font
Link: </app/style.css>; rel=preload; as=style
Such links, set on HTML page (like index.html ), will informs HTTP server to push the resources together with the response on your HTML page . As the result you save unneeded round-trips and the later requests (after parsing HTML files) and the resources will be displayed immediately. You can consider to set the LINK headers on all images from your page to improve the visibility of your page. See here additional information with nice pictures, which demonstrates the advantage of HTTP/2 server push. If you use PHP then the code could be interesting for you.
The most web developers do some optimizations steps directly or indirectly. The steps are done either during building process or by setting HTTP headers in HTTP responses. One have to review some processes switch off someone and include another one. I try to summarize my results.
- you can consider to use webpack instead of browserify to exclude some dependencies from merging. I don't know browserify good enough, but I know that webpack supports
externals(see here ), which allows to load some modules from CDN. In the next step you can remove any merging at all, but minimize and setcache-controlon all your modules. - It's strictly recommended to load CSS/JS/Fonts, which you use, and which you don't developed yourself, from CDN. You should never merge such resources with your JavaScript files (what could you probably do with browserify now). Loading of Bootstrap CSS from your server is not good idea. One should better follow advises from here and use CDN instead ol downloading of all files locally.
The main reason of the usage of CDN is very easy to understand if you examine HTTP headres of the response from https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.1/jquery.min.js for example. You will find something like cache-control: public, max-age=30672000 and expires:Mon, 06 Mar 2017 21:25:04 GMT . Chrome will shows typically Status Code:200 (from cache) and you will see no traffic over the wire. If you explicitly reload the page (by pressing F5 ) then you will see a response with 222 bytes and Status Code:304 . In other words the file will be typically didn't loaded at all. jQuery 2.2.1 stay forever the same . The next version will have another URL . The usage of HTTPS makes sure that the user will load really jQuery 2.2.1. If it's not enough then you can use https://www.srihash.org/ to calculate sha384 value and use extended form of <link> or <script> :
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.1/jquery.min.js"
integrity="sha384-8C+3bW/ArbXinsJduAjm9O7WNnuOcO+Bok/VScRYikawtvz4ZPrpXtGfKIewM9dK"
crossorigin="anonymous"></script>
If the user opens your page with the link then the sha384 hash will be recalculated and verified (by Chrome and Firefox). If the file is not yet in local cache then it will be loaded really quickly too. One short remark by loading the same file from https://code.jquery.com/jquery-2.2.1.min.js one uses HTTP 1.1 today, but from https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.1/jquery.min.js be used HTTP/2 protocol. i recommend to test the protocol by choosing the CDN. You can find here the list of CDNs which supports now HTTP/2. In the same way loading Bootstrap from https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css one would uses HTTP 1.1 today, but one would use HTTP/2 by loading the same data from https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.6/css/bootstrap.min.css .
I spend many time for CDN to make clear that the most advantage of CDN is setting of cashing headers of HTTP response and the usage of immutable URLs . You can do the same in your modules too.
- One should think about the time of caching of every content returned from the server. You can use URLs to your modules, which contains version number of your component (like
/script/mycomponent1.1.12341) and to change the last part of version number every time on changing the module. You can set long enough value ofmax-ageincache-controland your components will be cached by web browser of the client.
Finally I'd recommend you to verify that you installed the latest version of OpenSSL and the latest version of nginx . I recommend to verify your web site in http://www.webpagetest.org/ and in https://www.ssllabs.com/ssltest/ to be sure that you don't forget any simple steps.
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