TypeScript syntax (1) -- Basic Data Type

TypeScript syntax (1) -- Basic Data Type
1. Boolean)

var isDone: boolean = true;

2. Number)

var height: number = 6;

Iii. String type)

You can use double quotation marks or single quotation marks.

var name: string = "bob";name = 'smith';

4. Array)

Two methods to declare an array:

First:

var list:number[] = [1,2,3];

Note:numberIndicates the Data Type of elements in the array,[]Declares an array.

Second:

var list:Array
  
    = [1,2,3];
  

Note:ArrayDeclares an array, Indicates the Data Type of elements in the array.

5. Enumeration type (Enum)

enum Color {Red, Green, Blue};var c: Color = Color.Green;

By default, the index starting with a member of the enumeration type is0(RedThe index is0), You can manually change the start index of the member in the enumeration type, for example:

enum Color {Red = 1, Green, Blue};var c: Color = Color.Green;

RedThe index is1You can also specify an index for each member, for example

Enum Color {Red = 1, Green = 2, Blue = 4}; var c: Color = Color. Green; // note c: there is no space between each character of Color.

Value Through Index

enum Color {Red = 1, Green, Blue};var colorName:String = Color[2];alert(colorName);

6. Any type (Any)

A variable that describes unknown types, or the variable type changes dynamically. It must be declaredanyType to make the variable pass the variable type check during compilation.

var notSure: any = 4;notSure = "maybe a string instead";notSure = false;

Arrays containing different types of elements:

var list:any[] = [1, true, "free"];list[1] = 100;

7. No type (void)

The following function does not return any value

function warnUser(): void {    alert("This is my warning message");}