TypeScript 照猫画虎

定义变量类型

const num: number = 1

定义函数参数类型

const init: (p: str) => void
	= function(param) {
		alert(param)
	}

定义外部变量

declare var document
document.str = 'hello'

原始类型

var age: number = 2
var rating = 98.25
var isReady: boolean = true
var hasData = true
var firstName: string = 'John'
var lastName = 'Papa'

Arrays and Indexers

var names: string[] = ['John', 'Dan', 'Aaron', 'Fritz']
var firstPerson: string
firstPerson = names[0]

Null and Undefined

var num: number = null
var str: string = null
var isHappy: boolean = null
var customer: {} = null
var age: number;
var customer = undefined
var quantity: number
var company = undefined

---

对象类型

// object
var square = { h: 10, w: 20 }
var points: Object = { x: 10, y: 20 }
// function
var multiply = function (x: number) {
	return x * x
}
var multiplyMore: Function;
multiplyMore = function (x: number) {
	return x * *
}

Functions

image

var myFunc = function (h: number, w:number) {
	return h * w
}
var myFunc = (h: number, w: number) => h * w
// Void (Used as the return type for functions that return no value)
var greetMe : (msg: string) => void
greetMe = function (msg) {
	console.log(msg)
}
greetMe('Hello!')

Function Interface

interface SquareFunction {
	// 接收一个number类型参数，返回一个number类型的值
	(x: number): number
}
var squareItBasic: SquareFunction = num => num * num

interface Rectangle {
	h: number
	w?: number
}
squareIt: (react: Rectangle) => number