TypeScript学习笔记、鸿蒙开发学习笔记-编程知识

TypeScript学习笔记、鸿蒙开发学习笔记

变量定义方式

# 变量声明
let msg: string = 'douzi'
console.log(msg)
let num: number = 20
console.log(num)
let end: boolean = true
console.log("end=" + end)
let a: any = 10
a = 'douzi'
console.log(a)
let p = {name:"douzi",age:20}
console.log(p.name)
console.log("age=" + p['age'])
let names: Array<string> = ["douzi","douzi1"]
console.log(names[0])
let ages: number[] = [20,21]
console.log("age1=" + ages[1])

条件定义方式

# 条件语法
if(num % 2 == 0) {console.log("num 是偶数")
}else {console.log("num 是奇数")
}if (num > 0) {console.log("num 是正数")
}else if(num < 0){console.log("num 是负数")
} else {console.log("num 是0")
}# switch 
switch(msg) {case 'douzi': {console.log("douzi")break}case 'douzi1': {console.log("douzi1")break}default: {console.log('douzi2')break}
}

循环定义方式

# 循环语法
for(let i = 0; i < 10; i++) {console.log("for i=" + i)
}let i = 0;
while(i < 10) {console.log('while i=' + i ++)
}let names: Array<string> = ["douzi","yuehua"]
// for in 迭代器，获取数组角标  const = let
for (const i in names) {console.log(i + "=" + names[i])
}
// for of 迭代器，获取数组元素
for (const name of names) {console.log("of name = " + name)
}

函数定义方式

# 无返回值函数  :void 可以省略
function helloWorld(name:String, age:number): void {console.log("name=" + name + ",age=" + age + ",Hello World!")
}# 无返回值函数简写方式
let helloWorld = (name:String, age:number) => {console.log("name=" + name + ",age=" + age + ",Hello World!")
}helloWorld('douzi', 40)# 有返回值函数
function sum(x: number, y: number): number {return x + y
}# 有返回值函数简写方式
let sum = (x: number, y: number): number => {return x + y
}
let result = sum(10, 20)
console.log("10 + 20 = " + result)# 可选参数，？代表参数 可传 可不传
let sayHello = (name ?:String) => {name = name ? name : 'yuehua'console.log("Hello " + name)
}
sayHello()
sayHello('douzi')# 入参默认值 当不传参数时，使用默认值
let sayHello = (name :String = 'yuehua') => {console.log("Hello " + name)
}
sayHello()
sayHello('douzi')

类和接口的定义

# 接口继承
enum Msg {HI = 'Hi',HELLO = 'Hello'
}interface A {say(msg: Msg): void
}class B implements A {say(msg: Msg) {console.log(msg + ", I am B")}
}let a:A = new B()
a.say(Msg.HELLO)# 类继承
class Rectangle {private width: numberprivate height: numberconstructor(width: number,height: number) {this.height = height;this.width = width}    public area(): number {return this.width * this.height}
}
class Square extends Rectangle {constructor(side: number) {super(side, side)}
}let s:Square = new Square(5)
console.log('正方形边为5的area=' + s.area())