TypeScript学习笔记 （一）基础特性

一. 字符串新特性

　1. 多行字符串

　　var str = ``;　

　2. 字符串模板

　　

var world = "world";
var str = `hello ${world}`;

　3. 自动拆分字符串

　　

var myName:string = 'ts';
var myAge:number = 18;
var test = function(temp, name:string, age:number){
　　console.log(temp);
　　console.log(name);
　　console.log(age);
};
test`My name is ${myName}, and i'm ${myAge} years old`;

二、类型

1. 变量类型

var a: string = "";
var b: number = 1;
var c: boolean = true;
var d: any;
function test(name:string): void {

}

2. 可选参数和默认参数

function test(a:string, b?: number, c: number = 23){

      console.log(a);
      console.log(b);
      console.log(c);
}    

test("jojo");

三、函数新特性

1. Rest and Spread 操作符

　　用来声明任意数量的参数

// 函数定义是运用
function func1(...args){
      args.forEach(function(arg){
        console.log(arg);
    });
};

func1(1,2,3);
func1(1,2,3,4,5,6);

// 函数调用时运用
function func2(a,b,c){
    console.log(a);
    console.log(b);
    console.log(c);
}

var args1 = [1,2];
func2(...args1);
var args2 = [4,5,6,7,8,9];
func2(...args2);

2. generator函数

　　控制函数的执行过程，手工暂停和恢复代码执行

function* doSth(){
    console.log("start");
    yield;
    console.log("finish");
}
var func1 = doSth();

func1.next();
func1.next();

function* getStockPrice(stock){
      while(true){
            yield Math.random()*100;
    }
};

var priceGenerator = getStockPrice("IBM");
var limitPrice = 12;
var price = 100;
while(price > limitPrice){
    price = priceGenerator.next().value;
    console.log(`the generator return ${price)`);
};

console.log(`buy at ${price}`);

3. 析构表达式

　　通过表达式将对象或数组拆解成任意数量的变量

function getStock(){
    return {
        code: "IBM",
        price: {
            price1: 100,
            price2: 200
        },
        aaa: "xixi",
        bbb: "haha"
    }
}

// js
var stock = getStock();
var code = stock.code;
var price = stock.price;

// ts
var {code: codeAlias, price, price:{price2}} = getStock(); // 花括号中的变量要和方法中变量名字对应, codeAlias为别名

console.log(codeAlias);
console.log(price);
console.log(price2);

var array1 = [1,2,3,4,5,6,7];

var [,,number3,number4,...others] = array1;
console.log(number3);
console.log(number4);
console.log(others);

var array1 = [1,2,3,4,5,6,7];

function doSth([,,number3,number4,...others]){
    console.log(number3);
    console.log(number4);
    console.log(others);
};

doSth(array1);

四、表达式和循环

1. 箭头表达式

　　用来声明匿名函数，消除传统匿名函数的this指针问题

// 单行
var sum = (arg1, arg2) => arg1 + arg2;
// 多行
var sum1 = (arg1, arg2) => {
    return arg1 + arg2;
};
// 无参数
var sum2 = () => {
     console.log("无参数箭头表达式");
};
// 单个参数
var sum3 = arg1 => {
     console.log(arg1);
};
console.log(sum(1,2));
console.log(sum1(1,2));
console.log(sum2());
console.log(sum3(2));

var myArray = [1,2,3,4,5,6,7,8];
console.log(myArray.filter(value=>value%2 == 0));

function getStock(name:string){
    this.name = name;

    setInterval(function(){
        console.log("name is " + this.name);
    },1000);

    setInterval(()=>{
        console.log("name is " + this.name);
    }, 2000);
};

var stock = new getStock("jojo");

2. for of

var myArray = [1,2,3,4,5];

myArray.desc = "a array"; // js

myArray.forEach(value=>console.log(value));

for(var n1 in myArray){
  console.log(n1);
}

for(var n2 in myArray){
  console.log(myArray[n2]);
}

for(var n3 of myArray){
  console.log(n3);
}

for(var n4 of "i'm an array"){
  console.log(n4);
}