04.TypeScript函数新特性

1. Rest and Spread操作符

   任意数量的方法参数，restAndSpread.ts文件内容如下

   function test(...args ){
       args.forEach(function(arg){
           console.log(arg);
       });
   }
   
   test('aaa', 'bbb');
   test('aaa');
   
   function test2(a, b, c) {
       console.log(a);
       console.log(b);
       console.log(c);
   }
   
   var arr1 = [1, 2];
   var arr2 = [7, 8, 9, 10];
   test2(...arr1);
   test2(...arr2);
   

     编译后的restAndSpread.js文件内容如下

   function test() {
       var args = [];
       for (var _i = 0; _i < arguments.length; _i++) {
           args[_i] = arguments[_i];
       }
       args.forEach(function (arg) {
           console.log(arg);
       });
   }
   test('aaa', 'bbb');
   test('aaa');
   function test2(a, b, c) {
       console.log(a);
       console.log(b);
       console.log(c);
   }
   var arr1 = [1, 2];
   var arr2 = [7, 8, 9, 10];
   test2.apply(void 0, arr1);
   test2.apply(void 0, arr2);

    

2. generator函数

   实例1：generator1.ts文件内容如下

   function* doSomething() {
       console.log('start');
       yield;
       console.log('finish');
   }
   
   var func1 = doSomething();
   func1.next();
   func1.next();
   

   实例2：generator2.ts文件内容如下

   function* getStockPrice(stock) {
       while (true) {
           yield Math.random()*100;
       }
   }
   
   var priceGenerator = getStockPrice("IBM");
   
   var price = 100;
   var limitPrice = 15;
   
   while (price > 15) {
       price = priceGenerator.next().value;
       console.log(`the generator return ${price}`)
   }
   
   console.log(`buying at ${price}`);

     

3. 析构表达式

   对象的析构表达式，objectDestructuring.ts文件的内容如下

   function getStock() {
       return {
           code: '3938168',
           name:'IBM',
           price: {
               price1: 200,
               price2:400
           }
       }
   }
   
   var { code, name: stockName, price: { price2 } } = getStock();
   
   console.log(code);
   console.log(stockName);
   console.log(price2);

   编译后objectDestructuring.js的文件内容如下

   function getStock() {
       return {
           code: '3938168',
           name: 'IBM',
           price: {
               price1: 200,
               price2: 400
           }
       };
   }
   var _a = getStock(), code = _a.code, stockName = _a.name, price2 = _a.price.price2;
   console.log(code);
   console.log(stockName);
   console.log(price2);

   数组的析构表达式，arrayDestructuring.ts文件的内容如下

   var arr = [1, 2, 3, 4];
   var [number1, , , number2] = arr;
   console.log(number1);
   console.log(number2);
   
   arr = [5, 6, 7, 8];
   var [n1, n2, ...others] = arr;
   console.log(n1);
   console.log(n2);
   console.log(others);
   
   function test([n1,n2,...others]) {
       console.log(n1);
       console.log(n2);
       console.log(others);
   }
   
   test(arr);

   编译后arrayDestructuring.js的文件内容如下  

   var arr = [1, 2, 3, 4];
   var number1 = arr[0], number2 = arr[3];
   console.log(number1);
   console.log(number2);
   arr = [5, 6, 7, 8];
   var n1 = arr[0], n2 = arr[1], others = arr.slice(2);
   console.log(n1);
   console.log(n2);
   console.log(others);
   function test(_a) {
       var n1 = _a[0], n2 = _a[1], others = _a.slice(2);
       console.log(n1);
       console.log(n2);
       console.log(others);
   }
   test(arr);