typescript学习笔记（二）

类

设置存储器，get  set 访问成员

函数支持可选参数 ，可选参数必须放后面

<span><span>function</span> <span>buildName</span>(<span>firstName: <span>string</span>, lastName?: <span>string</span></span>) </span>{
    <span>if</span> (lastName)
        <span>return</span> firstName + <span>" "</span> + lastName;
    <span>else</span>
        <span>return</span> firstName;
}

<span>let</span> result1 = buildName(<span>"Bob"</span>);  <span>// works correctly now</span>
<span>let</span> result2 = buildName(<span>"Bob"</span>, <span>"Adams"</span>, <span>"Sr."</span>);  <span>// error, too many parameters</span>
<span>let</span> result3 = buildName(<span>"Bob"</span>, <span>"Adams"</span>);  <span>// ah, just right</span>

还支持默认参数

functionbuildName(firstName:string, lastName = "Smith") {}

剩余参数

functionbuildName(firstName:string, ...restOfName:string[]) {}

this方法，难点

泛型包括泛型方法和泛型类和模板类，类似。

特点是，方法参数兼容，类型兼容

交叉类型，可以是多个类组成的类型，实例化后，拥有多个类的方法和属性

var jim = extend(new Person("Jim"),new ConsoleLogger());

联合类型，只能访问，两种类型的交集，即公共部分

functiongetSmallPet():Fish |Bird{
    // ...
}

函数返回值可用=>指定