03. New features of TypeScript parameters

1. variable type

   The typeTest.ts file is as follows

   /**String type*/
   var myname: string = "xiaoming";
   
   /**Number type*/
   var age: number = 15;
   
   /**Boolean type*/
   var man: boolean = true;
   
   /**any type*/
   var alias:any = "alias";
   alias = 13;
   
   /**Method void type*/
   function test(name: string): void{
       
   }
   
   /**Custom type*/
   class Person{
       name: string;
       age: number;
   }
   
   var zhangsan: Person = new Person();
   zhangsan.age = 18;
   zhangsan.name = 'zhangsan';

    The compiled typeTest.js file is as follows

   /**String type*/
   var myname = "xiaoming";
   /**Number type*/
   var age = 15;
   /**Boolean type*/
   var man = true;
   /**any type*/
   var alias = "alias";
   alias = 13;
   /**Method void type*/
   function test(name) {
   }
   /**Custom type*/
   var Person = /** @class */ (function () {
       function Person() {
       }
       return Person;
   }());
   var zhangsan = new Person ();
   zhangsan.age = 18;
   zhangsan.name = 'zhangsan';

    

2. parameter default value

   The content of the defaultValue.ts file is as follows

   function test(a: string,b: string, c:string="zzz" ){
       console.log(a);
       console.log(b);
       console.log(c);
   }
   
   test('aaa', 'bbb');
   test('aaa', 'bbb', 'ccc');

     编译后defaultValue.js文件内容如下

   function test(a, b, c) {
       if (c === void 0) { c = "zzz"; }
       console.log(a);
       console.log(b);
       console.log(c);
   }
   test('aaa', 'bbb');
   test('aaa', 'bbb', 'ccc');

    

3. 可选参数

   optionalParameters.ts文件内容如下

   /**加？设置可选参数 */
   function test(a: string,b?: string, c:string="zzz" ){
       console.log(a);
       console.log(b);
       console.log(c);
   }
   
   test('aaa', 'bbb');
   test('aaa');
   

     编译后optionalParameters.js文件内容如下

   function test(a, b, c) {
       if (c === void 0) { c = "zzz"; }
       console.log(a);
       console.log(b);
       console.log(c);
   }
   test('aaa', 'bbb');
   test('aaa');