TYPESCRIPT

``Typescript is a strongly typed programming language that builds on JavaScript, giving you better tooling at any scale, it enables you to write JavaScript the way you want. it is a pure Object oriented programming language with class interface and static typing.

Why Use Typescript

• Compilation.
• Strong static typing.
• Supports type definition from existing JavaScript.
• Supports Object Oriented Programming Language.

Type System In Typescript.

• Any : This is a super type of all types in typescripts.

• Build In : This type consists of (String, Null, Number,
  Array, Undefined, Boolean, Void and so on).

• User Define Type : The user defines the kind of type. e.g
  (Classes, OOP and Enums)

How to declare an Array variable in Typescript.

The type syntax for declaring a variable in TypeScript is to include a colon (:) after the variable name, followed by its type. Just as in JavaScript, we use the var keyword to declare a variable. Declare its type and value in one statement.
When you declare a variable, you have four options −

1 Declare its type and value in one statement :
var [identifier] : [type] = value ;
2 Declare its type but no value. In this case, the variable will
be set to undefined:
var [identifier] : [type] ;
3 Declare its value but no type. The variable type will be set to
the data type of the assigned value.
var [identifier] = [value] ;
4 Declare neither value not type. In this case, the data type of
the variable will be any and will be initialized to undefined.
var [identifier] ;

Example: Variables in TypeScript

`
"use strict";

let a:number = 30;
a = "35";

let b:any = true
b = "red"
let c:undefined;
let z:null

let Uname:string = "Ade"
`

how to declare an object in Typescript
_
`
`var Data1: {
id : number | string;
name: string;
email: string;
height:number;
age: number;

}={
id : 234567890,
name: "adeola",
email: "[e-mail]",
height: 50,
age: 25,
};
``

How to declare an array in typescript
array

let carting: (string | number | boolean | null)[] = ["Addidas", 80, 90, null];