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27 lines
664 B
27 lines
664 B
import ReactDOM from "react-dom";
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// 函数的默认值
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type Props = { name: string; age?: number}
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// const Hello: FC<Props> = ( { name, age } ) => (
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// <div>我是：{name}, 我 { age } 岁</div>
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// )
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// 提供默认属性
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// Hello.defaultProps = {
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// age: 18 // age 是可选属性，当没给 age 的值时，默认 age 的值为 18
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// }
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// 简化写法
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const Hello = ( { name, age = 18 }: Props ) => ( // 给 age 添加默认值 18
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<div>我是：{name}, 我 { age } 岁</div>
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)
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const App = () => <div>
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{/* name 是必填的 */}
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<Hello name="jack" />
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</div>
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ReactDOM.render(<App />, document.getElementById('root'))
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