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# ?: 可选属性

有时我们希望不要完全匹配一个形状，那么可以用可选属性：

```typescript
interface Person {
    name: string;
    age?: number;
}

let tom: Person = {
    name: 'Tom'
};
```

```typescript
interface Person {
    name: string;
    age?: number;
}

let tom: Person = {
    name: 'Tom',
    age: 25
};
```

可选属性的含义是该属性可以不存在。