解释 JavaScript 中的回调 Promise.finally

javascriptweb developmentobject oriented programming

无论承诺已实现还是已拒绝，promise.finally() 都会调用回调函数。这有助于我们在承诺被拒绝或解决后执行某些操作。

以下是 JavaScript 中 Promise.finally() 的代码 −

示例

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   .result {
      font-size: 20px;
      font-weight: 500;
   }
</style>
</head>
<body>
<h1>Promise.finally in JavaScript</h1>
<div style="color: green;" class="result"></div>
<button class="btn">点击此处</button>
<h3>
Click on the above button to know when the promise finishes
</h3>
<script>
   let btnEle = document.querySelector(".btn");
   let resEle = document.querySelector(".result");
   const yearRegex = /(?\d{4})/g;
   btnEle.addEventListener("click", () => {
      fetch("https://jsonplaceholder.typicode.com/users")
      .then((Response) => Response.json())
      .then((res) => res)
      .catch((err) => alert("error occured"))
      .finally(() => (resEle.innerHTML = "Promise is finished"));
   });
</script>
</body>
</html>