typescript-crash-course

What is TypeScript?

• Language developed by Microsoft in 2012 - Free and Open source
• Provides static typing support to JavaScript. It has IDE Support: code completion and debugging
• Add Support for object-oriented programming - classes, objects, inheritance, interfaces etc
• TypeScript is a superset of JavaScript and ECMAScript
• Strongly-typed language with compile time checking and IDE support
• The Angular framework is internally developed using typescript
• Docs, online blogs and tutorials use TypeScript for coding examples
• For complete reference - www.typescriptlang.org

Setting up Development Tools

Tool	Purpose
node	For running JavaScript code from command-line
npm	Node Package Manage - Download new node packages and feature. Similar to maven
tsc	TypeScript compiler

TypeScript - Terminology

• First TypeScript Application - Example

• Defining Variables:

  • Syntax - let <variableName>: <type> = <initial value>;

Type	Description	Example
boolean	true/false values	Example
number	supports integer and floating point	Example
string	text data. enclosed in single or double quotes	Example
any	Supports "any" datatype assignment	Example
others	See details at www.typescriptlang.org

• Loop and Arrays - Example

• Access Modifiers

Modifier	Definition
public	Property is accessible to all classes (default modifier)
protected	Property is only accessible in current and sub classes
private	Property is only accessible in current class

• Classes

  • Class Definition - Example
  • Access Modifiers - Example
  • Parameter Properties - Example

• tsconfig

  • Configuration file for TypeScript - Example

• Module import and export

  • import - import {<ClassName>} from "<Absolute Path of the file whereclass is defined>" - Example
  • export - just add export before class name - Example

• Inheritance - Example

  • Define common properties and methods in the superclass
  • Subclasses can extend superclasses and add properties and methods
  • Support for abstract classes and overriding
  • Support only single inheritance
  • However we can implement multiple interfaces

• Abstract Class - Example

  • An abstract class represents a general concept - for example: Shape, Vehicle, Computer etc...
  • We can't create an instance of an abstract class
  • Abstract class can also have abstract method(s)
  • Abstract method must be implemented by concrete subclasses

• Interfaces - Example

  • Define an interface with a method contract
  • Classes implement the interface accordingly
  • A class can implement multiple inheritances

• Compiling and Executing the TypeScript

  • tsc <fileName.ts> - to compile the specific file or type tsc to compile all the typescript files in directory.
  • node <fileName.js> - to run the java script file