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7个技巧让你写出干净的 TSX 代码

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11/12
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1. 为所有值提供显式类型

使用 TypeScript 时，很多人经常不为值提供显式类型，从而错失 TS 在开发中的真正用处

坏栗子 01:

const Component = ({ children }: any) => {
  // ...
};

坏栗子 02:

const Component = ({ children }: object) => {
  // ...
};

恰当地使用interface 能够让编辑器给你提供准确的提示，从而让敲代码变得更容易

好栗子:

import { ReactNode } from "react";

interface ComponentProps {
  children: ReactNode;
}

const Component = ({ children }: ComponentProps) => {
  // ...
};

相关问答

Q1: 2. 更新状态时考虑先前的状态

如果更新状态时新状态依赖于旧状态，在调用更新状态函数时传入函数来更新状态，React 状态更新会进行批处理，如果不使用这种方式更新状态很可能导致意想不到的结果

坏栗子:

import React, { useState } from "react";

export const App = () => {
  const [isDisabled, setIsDisabled] = useState(false);

  const toggleButton = () => {
    setIsDisabled(!isDisabled);
  };

  // 此处调用两次toggleButton的结果和调用一次相同
  const toggleButtonTwice = () => {
    toggleButton();
    toggleButton();
  };

  return (
    <div>
      <button disabled={isDisabled}>
        I'm {isDisabled ? "disabled" : "enabled"}
      </button>
      <button onClick={toggleButton}>
        Toggle button state
      </button>
      <button onClick={toggleButtonTwice}>
        Toggle button state 2 times
      </button>
    </div>
  );
};

好栗子:

import React, { useState } from "react";

export const App = () => {
  const [isDisabled, setIsDisabled] = useState(false);

  const toggleButton = () => {
    setIsDisabled((isDisabled) => !isDisabled);
  };

  const toggleButtonTwice = () => {
    toggleButton();
    toggleButton();
  };

  return (
    <div>
      <button disabled={isDisabled}>
        I'm {isDisabled ? "disabled" : "enabled"}
      </button>
      <button onClick={toggleButton}>
        Toggle button state
      </button>
      <button onClick={toggleButtonTwice}>
        Toggle button state 2 times
      </button>
    </div>
  );
};

Q2: 3. 保持文件原子性和精简性

保持稳健的原子性和精简性可以让调试、维护甚至查找文件更加容易

坏栗子:

// src/App.tsx
export default function App() {
  const posts = [
    {
      id: 1,
      title: "How to write clean react code",
    },
    {
      id: 2,
      title: "Eat, sleep, code, repeat",
    },
  ];

  return (
    <main>
      <nav>
        <h1>App</h1>
      </nav>
      <ul>
        {posts.map((post) => (
          <li key={post.id}>
            {post.title}
          </li>
        ))}
      </ul>
    </main>
  );
}

好栗子:

// src/App.tsx
export default function App() {
  return (
    <main>
      <Navigation title="App" />
      <Posts />
    </main>
  );
}

// src/components/Navigation.tsx
interface NavigationProps {
  title: string;
}

export default function Navigation({ title }: NavigationProps) {
  return (
    <nav>
      <h1>{title}</h1>
    </nav>
  );
}

// src/components/Posts.tsx
export default function Posts() {
  const posts = [
    {
      id: 1,
      title: "How to write clean react code",
    },
    {
      id: 2,
      title: "Eat, sleep, code, repeat",
    },
  ];

  return (
    <ul>
      {posts.map((post) => (
        <Post key={post.id} title={post.title} />
      ))}
    </ul>
  );
}

// src/components/Post.tsx
interface PostProps {
  title: string;
}

export default function Post({ title }: PostProps) {
  return <li>{title}</li>;
}

Q3: 4. 对具有多个状态的值使用枚举或常量对象

使用枚举或常量对象可以大大简化管理存在多种状态的变量的过程

坏栗子:

import React, { useState } from "react";

export const App = () => {
  const [status, setStatus] = useState("Pending");

  return (
    <div>
      <p>{status}</p>
      <button onClick={() => setStatus("Pending")}>
        Pending
      </button>
      <button onClick={() => setStatus("Success")}>
        Success
      </button>
      <button onClick={() => setStatus("Error")}>
        Error
      </button>
    </div>
  );
}

好栗子:

import React, { useState } from "react";

enum Status {
  Pending = "Pending",
  Success = "Success",
  Error = "Error",
}
// OR
// const Status = {
//   Pending: "Pending",
//   Success: "Success",
//   Error: "Error",
// } as const;

export const App = () => {
  const [status, setStatus] = useState(Status.Pending);

  return (
    <div>
      <p>{status}</p>
      <button onClick={() => setStatus(Status.Pending)}>
        Pending
      </button>
      <button onClick={() => setStatus(Status.Success)}>
        Success
      </button>
      <button onClick={() => setStatus(Status.Error)}>
        Error
      </button>
    </div>
  );
};

Q4: 5. 尽量不在视图中编写逻辑

尽量不要把逻辑代码嵌入到标签中

坏栗子:

const App = () => {
  return (
    <div>
      <button
        onClick={() => {
          // ...
        }}
      >
        Toggle Dark Mode
      </button>
    </div>
  );
};

好栗子:

const App = () => {
  const handleDarkModeToggle = () => {
    // ...
  };

  return (
    <div>
      <button onClick={handleDarkModeToggle}>
        Toggle Dark Mode
      </button>
    </div>
  );
};

当然如果逻辑代码只有简单的一行，写在标签中也是可以的

Q5: 6. 正确地选择条件渲染的方式

正确地选择条件渲染的方式可以让代码更优雅

坏栗子:

const App = () => {
  const [isTextShown, setIsTextShown] = useState(false);

  const handleToggleText = () => {
    setIsTextShown((isTextShown) => !isTextShown);
  };

  return (
    <div>
      {isTextShown ? <p>Now You See Me</p> : null}

      {isTextShown && <p>`isTextShown` is true</p>}
      {!isTextShown && <p>`isTextShown` is false</p>}

      <button onClick={handleToggleText}>Toggle</button>
    </div>
  );
};

好栗子:

const App = () => {
  const [isTextShown, setIsTextShown] = useState(false);

  const handleToggleText = () => {
    setIsTextShown((isTextShown) => !isTextShown);
  };

  return (
    <div>
      {isTextShown && <p>Now You See Me</p>}

      {isTextShown ? (
        <p>`isTextShown` is true</p>
      ) : (
        <p>`isTextShown` is false</p>
      )}

      <button onClick={handleToggleText}>Toggle</button>
    </div>
  );
};

Q6: 7. 使用JSX简写

布尔属性

一个具有真值的属性可以只写属性名，比如truthyProp，而不必写成truthyProp={true}

坏栗子:

interface TextFieldProps {
  fullWidth: boolean;
}

const TextField = ({ fullWidth }: TextFieldProps) => {
  // ...
};

const App = () => {
  return <TextField fullWidth={true} />;
};

好栗子:

interface TextFieldProps {
  fullWidth: boolean;
}

const TextField = ({ fullWidth }: TextFieldProps) => {
  // ...
};

const App = () => {
  return <TextField fullWidth />;
};

字符串属性

属性值为字符串字面量可以直接用双引号包裹

坏栗子:

interface AvatarProps {
  username: string;
}

const Avatar = ({ username }: AvatarProps) => {
  // ...
};

const Profile = () => {
  return <Avatar username={"John Wick"} />;
};

好栗子:

interface AvatarProps {
  username: string;
}

const Avatar = ({ username }: AvatarProps) => {
  // ...
};

const Profile = () => {
  return <Avatar username="John Wick" />;
};

Undefined 属性

和普通的TS/JS一样，如果属性未提供值，则为undefined

坏栗子:

interface AvatarProps {
  username?: string;
}

const Avatar = ({ username }: AvatarProps) => {
  // ...
};

const Profile = () => {
  return <Avatar username={undefined} />;
};

好栗子:

interface AvatarProps {
  username?: string;
  // OR `username: string | undefined`
}

const Avatar = ({ username }: AvatarProps) => {
  // ...
};

const Profile = () => {
  return <Avatar />;
};

现在你应该知道怎么编写干净的 TSX 了

完结！撒花！

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