Typescript notes

// Typescript  install 、 compile 
//  In the use of  npm  Before the command   Must install  node.js

//  install 
	npm install -g typescript
	cnpm install -g typescript
	yarn -g add typescript

//  function 
	tsc helloworld.ts
	node helloworld.js

//  install  yarn  And  cnpm
	npm install -g yarn
	npm install -g cnpm

// Typescript  development tool  Vscode  Automatic compilation  .ts  file 
 1. tsc --int  Generate configuration files  tsconfig.json
 2.  modify  tsconfig.json,  Open notes  outDir: './js'
 3.  choice   terminal  ->  Run the task  -> tsc: monitor -tsconfig.json  Then you can automatically monitor the code dynamically 

typescript  data type ：
	boolean  Boolean type 
	number  Numeric type 
	string  String type 
	array  An array type 
	tuple  A tuple type 
	enum  Enumeration type 
	any  Any type 
	null
	undefined
	void  Empty type 
	never

//  Function declaration method ：
	function func ():string{
     // sting  Specify the type returned by the function 
		return '123123' 
	}
//  Anonymous functions 
	const func = function ():number {
    
	
	}
//  Functions with parameters 
	function func (name: string, age: number): string {
    
	return `${
      name}-${
      number}`
}
//  Functions that do not return values   No,  return  Function of 
	function func ():void {
    
	}
//  Function with optional arguments ( Optional parameters must be configured after mandatory parameters )
	function func (name:string,age?:number):string {
    
		return ' Optional parameter function ' // name  Must pass parameters ,age  Transmissible parameters 
	}
//  Default parameter function 
function func (name: string, age:number=30):string{
    
	retun ' Return string '  // age  Set default parameters 
}
//  Three point operator   Receive the value of the new parameter 
function func (...arg:number[]):number{
     // arg = [1,2,3,4]
	return ' Returns the number type ' //  The expansion operator receives the remaining parameters 
}

func(1,2,3,4)
function func(arg1:number, arg2:number, ...arg3:number[]):number{
    

	return ' Returns the number type ' // arg1=1, arg2=2, arg3=[3,4,5,6]
}

func(1,2,3,4,5,6)

//  function overloading 
	java  Overload of methods in ： Overloading refers to two or more functions with the same name ,  But they have different parameters ,  In this case, there will be overloading of functions 
	typescript  Heavy load in ,  Try the purpose of multiple functions by providing multiple function type definitions for the same function .
	// es5  A method with the same name appears ,  The following will replace the above method 
	function func (name;string):string
	function func (age:number):string
	function func (str:any):any{
    
		if (typeof str==='string') {
    
			return `${
      str}-- name `
		} else {
    
			return `${
      str}-- Age `
		}
	}

//  Inside the arrow function  this  Point to context