TypeScript Recipe: Type Transformations in Practice

Compile-time errors are the best help to avoid mistakes during writing the code and prevent potential runtime-errors

So let's squeeze some juice from Ts Mapped types

Keynote: Quick Creation of Angular2 App

This article is about fast setup & start working on your ng2 application.

The process feels quite similar to Node modules creation through npm CLI commands, but here we will use Angular Command Line Interface (Angular-CLI).

Keynote: Quick Creation of Node.js Module

This is short note about fast creation, publishing & using Node.js module via using Command Line Interface.

• Use npm init to create package.json.
• Run npm install --save to install dependency and save it to package.json.

When the code in the foo package does require('bar'), it will be loaded either foo/node_modules/bar or from core modules if it was installed as a global module via nmp install -g command.

Git tips & tricks: Merge vs Rebase (When to use?)

Keeping a clean history and smooth git workflow comes down to knowing the base use-cases & rules.

Rebases are how changes should pass from the top of hierarchy downwards and merges are how they flow back upwards.

---

• Use git pull --rebase when pulling changes from origin.
• Use git merge when merging feature branch changes back to master.

Rebasing Deletes Merge Commits! Never rebase master onto your feature branch!
see also –preserve-merges flag.

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Using merge when pulling changes from origin ties two histories together creating interleaved messy thread of histories:

• Interleaved history during merge: their feature X, my feature Y, their feature X, my feature Y...
• Linear history during rebase: their feature X, their feature X, my feature Y, my feature Y...

Keynote: URL types

More or Less, everyone could imagine what is URL, cause most web browsers display it in the address bar.
At the same time, if we'll dig dipper, many of the software engineers are not aware of the all use cases or even URL types.
So, here are some short-notes to refresh your memory. ---- ## Syntax Every HTTP URL conforms to the syntax of a generic URI. A generic URI is of the form: ``` scheme:[//[user:password@]host[:port]][/]path[?query][#fragment] ```

Keynotes: Derive JPA query from method name

JPA lookup

The JPA module supports defining a query or native query manually as String (using @NamedQuery/@NativeNamedQuery/@Query annotations) or have it being derived from the method name.

Default lookup strategy is CREATE_IF_NOT_FOUND, which combines combines CREATE and USE_DECLARED_QUERY ones. It looks up a declared query first, and if no declared query is found, it creates a custom method name-based query.

Spring Data repository query building mechanism allows quick query definition by method names & custom-tuning of it by introducing declared queries as needed.

Ketnote: AngularJS Filters

Angular JS

The Filters become handy first of all for the output formatting. Here are some regular angular filers:

• lowercase/upercase {{ uppercase_expression | uppercase}}
  
  

  {{'london' | upercase}}   > LONDON



• currency (Adds currency symbol)
  {{ currency_expression | currency : symbol : fractionSize}}
  
  

  {{amount | currency:"USD$"}}  > USD$350



• number (Formats a number as text)
  {{ number_expression | number : fractionSize}}
  
  

  {{ 97.523 | number:2}}  > 97.52



• date (Formats date by template)
  {{ date_expression | date : format : timezone}}
  
  

  {{'1288323623006' | date:"MM/dd/yyyy 'at' h:mma"}} 
   > 10/29/2010 at 6:40AM

  {{note.created | date:"'Created on a' EEEE 'in' MMMM"}} 
   > Created on a Friday in October
  



• json (Converts a JavaScript object into JSON string)
  {{ json_expression | json : spacing}}
  
  

  {{ {'name':'value'} | json }}  > {"name": "value"}

Keynote: AngularJS Services

Angular JS

To share the reusable logic & prevent duplication we've to use services:

• Value (Used Often) - simplest recipes, that shares value through the app repeatedly.


• Factory (Most Commonly Used) - shares methods and objects.


• Service (Rarely Used) - shares instances of methods and objects.


• Provider (Commonly Used like Configurable Factory) - shares methods & objects but allows configuration.


• Constant (Commonly Used) - shares the constant values within app configuration.

Git Tips & Tricks: Make the current commit the only (initial) commit

Here is the brute-force approach, which also removes the configuration of the repository.

Keynote: Regexp Short Notes

Regular expressions

Regular expression is a pattern describing a certain amount of text. So, Regexps are quite useful whatever programming language u're using.

Keynote: AngularJS Less Backend

Angular JS

Take a look on the previous article to refresh your memory

• Angular JS Basics shornotes.
• Angular JS Do the regular things.
• Angular JS Do the custom things.
• Angular JS Routing.

## Mock the Backend Responses With using an Angular module called `ngMockE2E` u can mock the Back-end responses data, so u can develop without real BE ready. * When you sent some requests via `$http` service the responses with the locally mocked data would be returned by `$httpBackend`. * You can use it for the Unit Testing as well.

Keynote: AngularJS Routing

Angular JS

Take a look on the previous article to refresh your memory

• Angular JS Basics shornotes.
• Angular JS Do the regular things.
• Angular JS Do the custom things.

## Routing With using an Angular module called `ngRoute` u can to create a layout template and to have multiple views by adding routing. * So, when you now navigate to `app/`, you are redirected to `app/index.html/#/users` and the users list appears in the browser. * Or, when u click add note the url changes to `app/index.html#notes/new` so template for adding the new note is displayed. ---- ## Add the application routing To use routing u've to declare your module with `ngRoute` dependency. *app.js* angular.module('MyApp', ['ngRoute']) .config(['$routeProvider', function($routeProvider) { $routeProvider .when('/notes', { templateUrl: 'templates/pages/notes/index.html' }) .when('/users', { templateUrl: 'templates/pages/users/index.html' }) .when('/notes/new', { templateUrl: 'templates/pages/notes/edit.html' }) .when('/', { redirectTo: '/users' }) .otherwise({redirectTo: '/notes'}); }]);

Keynote: Use Vagrant - forget "works on my machine" bugs

Vagrant

If you're a developer, Vagrant will isolate dependencies and their configuration within a single disposable, consistent environment, without sacrificing any of the tools you're used to working with (editors, browsers, debuggers, etc.). Once you or someone else creates a single Vagrantfile, you just need to vagrant up and everything is installed and configured for you to work. Other members of your team create their development environments from the same configuration, so whether you're working on Linux, Mac OS X, or Windows, all your team members are running code in the same environment, against the same dependencies, all configured the same way.
Say goodbye to "works on my machine" bugs.

Keynote: AngularJS do the custom things

Angular JS

Take a look on the previous article to refresh your memory

• Angular JS Basics shornotes.
• Angular JS Do the regular things.

## Directives Directive it's just html annotation in some div that triggers corresponding js behavior. <!-- directive ---- controller name -- alias to controller--> <div ng-controller="StoreController as store"> *Note: the alias is only visible only whithin this div.* **Include directive** * **ng-include** - allows to include the specified file into your elements. `<div ng-show="tab.isSet(1)" ng-include="'product-description.html'">` *Note: pass the name directly as a string using the single quotes `('...')`* ---- ## Custom directive Instead of using `ng-include` e.g. `<h3 ng-include="'product-title.html'"></h3>` you can create a custom directive e.g. `<product-title></product-title>`. The main benefit of the using the custom directives is that those allows you to write HTML that expresses the behaviour of your application. Directives can also be used for: * Expressiong the Complex UI * Calling events and registering event handlers * Reusing common components

Keynote: AngularJS do the regular things.

Angular JS

Take a look on the previous article to refresh your memory
Angular JS Basics shornotes. ## Angular Entities Overview DMCE are base AngularEntities to work with: * **Directives** – HTML annotations that trigger Javascript behaviors. * **Modules** – Where our application components live. * **Controllers** – Where we add application behavior. * **Expressions** – How values get displayed within the page.

Keynote: AngularJS Basic Short Notes

Angular JS

Superheroic JavaScript MVW Google Framework.
Google framework popular for Single Page Applications building.
Angular is used worldwide especially as enterprise way of building powerful web apps.
The new 2.0 version of Angular is focused on ECMAScript 6 and probably won't be compatible with the 1.4
Angular is used by: youtube, lynda.com, netflix, etc.

Keynote: Java try-with-resources Statement

The try-with-resources statement ensures that each resource is closed
at the end of the statement.
Otherwords, in try-with-resources statement any catch or finally block is run after the resources declared have been closed.

*Resource - is an object that must be closed after the program is finished with it.

Closing a stream when it's no longer needed is very important to avoid serious resource leaks.
Use try-with-resources or close those in finally block to guarantee that both streams will be closed even if an error occurs.

Keynote: Threads like trains:)

Using the Threads leverage your application speed & flexibility:

A thread can be only in one of five states:

State	Description
New	When created but not started - not alive yet.
Runnable	Eligible to run. either when start() method is invoked or returned or coming back from a blocked, waiting, or sleeping state - alive.
Running	The scheduler chooses a thread from the runnable pool and it becomes the currently executing process.
Wait/blocking/sleeping	The thread is still alive, but is currently not eligible to run. - considered alive.
Deads	run() method completed - it's no longer a separate thread of execution and never be brought back to life! If you invoke start() on a dead Thread instance, you'll get a runtime exception. - not alive.

Keynote: Understand Java Collections

Collections API based on the following flavors:

Interface	Description
Lists	Lists of things ordered by index
Sets	Groups of Unique things (without duplicates)
Maps	Key-Value entries with unique Keys
Queues	Items arranged by the order to be processed (FIFO/LIFO)

Notice, that Map-related collections do not implement java.util.Collection:

Keynote: Exceptions in Action

Preamble

The java.lang.Throwable class is the superclass of all errors and exceptions in the Java language.
It means that you can throw and catch only objects that inherit this class.

Catch or Specify Requirement

If you invoke some method that throws some Checked exception, you have to wrap it into try catch or add it to the method declaration! Otherwise - Compile Error!

*Checked exceptions - the class Exception and any subclasses that are not also subclasses of RuntimeException

• So, Exception and its subclasses(checked exceptions), except RuntimeException, are under Catch or Specify Requirement!
• Error, RuntimeException(unchecked exception) and their descendants are not under Catch or Specify Requirement!

If the runtime system exhaustively searches all the methods on the call stack
without finding an appropriate exception handler, the runtime system (and, consequently, the program) terminates!

So, Exception can be specified even in main method and forwarded out of application.
VM will exit in this case, if such exception happens.