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javascript - 异步等待函数未在事件监听器中执行

转载 作者：行者123 更新时间：2023-11-30 13:45:37 29 4
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我正在尝试调用 Trip Advisor API 并使用异步/等待函数返回一些数据。

async/await 函数定义在名为 req.js 的文件中，代码如下:

const findRest = async (reviews, closed) => {
  const respond = await fetch(
    "https://tripadvisor1.p.rapidapi.com/restaurants/list-by-latlng?limit=30&currency=EUR&distance=2&lunit=km&lang=en_US&latitude=53.3498&longitude=-6.2603",
    {
      method: "GET",
      headers: {
        "x-rapidapi-host": "tripadvisor1.p.rapidapi.com",
        "x-rapidapi-key": "x-rapidapi-key"
      }
    }
  );

  if (respond.status === 200) {
    let data = await respond.json();
    let newData = await data.data;

    let data1 = await newData.filter(
      review => parseInt(review.num_reviews) >= reviews
    );
    let data2 = await data1.filter(close => close.is_closed == closed);
    return data2;
  } else {
    throw new Error("Could not provide results within specified parameters");
  }
};

当事件监听器通过单击小窗体中的按钮触发时将调用它。此代码位于名为 app.js 的文件中，如下所示:

document.getElementById("subButton").addEventListener("click", function(e) {
  const userReviews = parseInt(document.querySelector(".userRev").value);
  const userClose = document.querySelector(".userClose").value;

  e.preventDefault();
  console.log("click");
  console.log(e.target.id);

  findRest(userReviews, userClose)
    .then(data =>
      data.forEach(element =>
        console.log(
          `${element.name} matches your search criterea and is located at ${element.address}
        To make a booking, please call ${element.phone}`
        )
      )
    )
    .catch(err => console.log(err));
});

此处供引用的是 HTML:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width,initial-scale=1" />
    <title>API Tester</title>
    <meta name="author" content="Phil My Glass" />
    <meta
      name="description"
      content="An app to help me practice my API calling"
    />
  </head>
  <body>
    <header>
      <h1>What Restaurant?</h1>
    </header>
    <main>
      <form id="form">
        <input id="userRev" class="userRev" /><br />
        <input id="userClose" class="userClose" />
        <button id="subButton" class="subButton" type="submit">Find!</button>
      </form>
    </main>
  </body>
  <script src="req.js" type="text/Javascript"></script>
  <script src="app.js" type="text/Javascript"></script>
</html>

当我在 app.js 文件中但在事件监听器外部运行 findRest 函数并将参数作为静态数据传递时，它只执行查找并将所有请求的数据打印到控制台。一旦我尝试在事件监听器中运行它，就什么也没有发生。没有返回的数据打印，没有错误，这让我很困惑。

就像我说的，它在事件监听器之外工作正常，但我已经尝试将 forEach 更改为映射，但仍然没有返回任何内容。有人可以帮忙吗!

最佳答案

回答

从评论和您的回复来看:没有任何事情发生的原因是因为数据是一个空数组。Array.forEach(callback) 仅在数组包含元素时执行回调。

它可能为空的原因是 restaurant.is_closed 的过滤器可能需要一个 bool 值，而您传入​​的是一个字符串(输入元素的值是一个字符串)。

最好使用复选框来查看它是否被选中。否则，您必须查看字符串输入是否匹配“true”或“false”。

代码本身

findRest 包含不必要的等待。您应该将其定义为

async function findRest(reviews, closed) {
  const response = await fetch(
    "https://tripadvisor1.p.rapidapi.com/restaurants/list-by-latlng?limit=30&currency=EUR&distance=2&lunit=km&lang=en_US&latitude=53.3498&longitude=-6.2603",
    {
      method: "GET",
      headers: {
        "x-rapidapi-host": "tripadvisor1.p.rapidapi.com",
        "x-rapidapi-key": "x-rapidapi-key"
      }
    }
  );

  if (response.status === 200) {
    // The only async call is casting the response to a JavaScript object
    const json = await response.json();
    console.log(json);
    const data = json.data;
    // Filtering the array is not async
    return data.filter((restaurant) => {
      // Adding some additional debugs to prove my hypothesis right
      const hasEnoughReviews = restaurant.num_review >= reviews;
      const isClosed = restaurant.is_closed === closed;
      console.log(`review debug: ${typeof restaurant.num_review}, ${typeof reviews} -> output: ${hasEnoughReviews}`);
      console.log(`closed debug: ${typeof restaurant.is_closed}, ${typeof closed} -> output: ${isClosed}`)
      return hasEnoughReviews && isClosed

    })
  } else {
    throw new Error("Could not provide results within specified parameters");
  }
}

您还可以在 eventListener 回调中使用 async/await，创建更简洁的代码

document.getElementById("subButton").addEventListener("click", async (e) => {
  const userReviews = parseInt(document.querySelector(".userRev").value);
  // Judging by the filter in the findRest, this should be a boolean?
  const userClose = document.querySelector(".userClose").value;

  e.preventDefault();
  console.log("click");
  console.log(e.target.id);

  try {
    const restaurants = await findRest(userReviews, userClose);
    // I think your issue is that restaurants is an empty array
    console.log(restaurants)
    restaurants.forEach(restaurant => {
      console.log(`${restaurant.name} matches your search criterea and is located at ${restaurant.address}
        To make a booking, please call ${restaurant.phone}`)
    })
  } catch (err) {
    console.log(err)
  }
});

关于javascript - 异步等待函数未在事件监听器中执行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/59390307/

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