Post About Rxjs

What can i say about rxjs?

Rxjs it is a different way of writing the code
For instance, instead of doing this:

document.querySelector('h1').addEventListener('click',(e)=>{
  alert()
}) 

With Rxjs you can write the same thing using this code:

Rx.Observable.fromEvent(document.querySelector('h1'),'click').subscribe((x)=>{
  alert()
})

So whats the advantage of using rxjs?

One of the advantages - is that you can use plenty of various utils which helps you:
For example if you want you code to respond not more than one events per second you can simply write this code:

Rx.Observable.fromEvent(window,'resize')
.throttleTime(1000)
.subscribe((x)=>{
  document.querySelector('h1').innerText =window.outerHeight
})

Which is nice
link to running code

Angular and AOT

Intro

It is a long time since i started to play with new angular (currently 5 beta). Currently i found that i know very little about AOT feature, so i think, it is good time to write a post about it.

So, What is this AOT thing about?

AOT - means Ahead Of Time Compilation, but what exactly is being compiled? after all we talking about javascript - an interpreted language which needs no compilation!
According to that it saying at angular site - the AOT is configuration that makes angular to precompile the HTML templates of components, and thus saves the the HTML processing (here is that "compilation" means in this case) from being performed at application runtime.

Sounds Like A Good Thing, So How Can I Get It In My Project?

If you use angular-cli tool for your project scaffolding it is very easy: Instead of usual

ng serve 

command, you can use

ng serve  --aot=true

command
You can see the difference in chrome dev tool:
ng serve

ng serve --aot=true

As you can see - the load time reduced to almost half size with AOT option

Source Maps

In this post i will talk a little about source maps - what are they and which problem they solve, and how to get them in your project.
So, if you sitting comfortably - lets begin

Minification

It pretty common that in nowadays project all javascript files are minified (or uglyfied) and concatenated into one file. Why?
Because to have project devided to many files(although it is convenient for developers) makes loading process slower (less performant).
Also it is a good practice not to expose your javascript logic to everybody...
But what about debugging the minified code? is it possible?

Source Maps

The answer is - yes, but (there is always a catch!) you must first configure the source map task to run alongside with magnification task. Source maps - are files (decorated with .map extension) which generated during uglification, which are (citing from this great guy) - links pieces of your minified bundle back to the original, unbuilt files.

How to get it work inside you project?

That is easy: Assuming that you have minification task run by Grunt-contrib-uglify task, all you need to do is to add following option:

...
uglify: {
    dist: {
        src: ['<%= src.js %>'],
        options: {
            sourceMap: true // - this will do the magic!
        },
        dest: '<%= distdir %>/js/<%= pkg.name %>.min.js'
    }
},
...

And now, after running grunt build task (which includes uplifting) you can see in your distilled folder the ".map" files and ,once you open your chrome dev tools and try to search for some line of your code - you will see the following picture:

Thats all - now you have source maps in your project...

One more trick

Of course - source maps are good as long as we talking about dev environment. In order not to create them at your production environment you can use conditional configuration:

...
uglify: {
    dev: {
        src: ['<%= src.js %>'],
        options: {
            sourceMap: true
        },
        dest: '<%= distdir %>/js/<%= pkg.name %>.min.js'
    },
    prod: {
        src: ['<%= src.js %>'],
        dest: '<%= distdir %>/js/<%= pkg.name %>.min.js'
    }
}
...
grunt.registerTask('prod', ['recess:min', 'uglify:prod', 'copy'])

Now, for production build you can simply call:

 node_modules/.bin/grunt prod