Typescript Introduction

Data type	Keyword	Description
Number	number	Double precision 64-bit floating point values. It can be used to represent both, integers and fractions.
String	string	Represents a sequence of Unicode characters
Boolean	boolean	Represents logical values, true and false
Void	void	Used on function return types to represent non-returning functions
Null	null	Represents an intentional absence of an object value.
Undefined	undefined	Denotes value given to all uninitialized variables

TypeScript provides data types as a part of its optional Type System. The data type classification is as given below −

let a: number      //e.g 1, 2, 3
let b: boolean     //e.g true, false
let c: string      //e.g "abel agoi"
let d: any         //this can take any other types
let e: number[]    //array of numbers e.g [1, 3, 54]
let f: any[]       //any array e.g [1, "abel agoi", true]

Arrow function:
In javascript, we can declare a function like below:

let log = function (message) {

  console.dir(message); 

}

You can also use the arrow function (=>) to achieve the same thing in typescript like below

let log = (message) => { //we simply remove the function 
 console.dir(message);
}

//above can even be shorten to
let log = (message) => console.dir(message);

//and if you are only passing one parameter, it can be shorten to
let log = message => console.dir(message); //not readable though