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JavaScript 中的 Promise 允许我们进行异步操作，在创建 promise 时并不知道其值。promise 可处于三种状态：挂起、完成和拒绝。
以下是 JavaScript 中 promise 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;
}
.sample {
font-size: 18px;
font-weight: 500;
color: red;
}
</style>
</head>
<body>
<h1>JavaScript Promises</h1>
<div class="sample"></div>
<button class="Btn">CLICK HERE</button>
<h3>
Click on the above button to display username using promises
</h3>
<script>
let sampleEle = document.querySelector(".sample");
document.querySelector(".Btn").addEventListener("click", () => {
fetch("https://jsonplaceholder.typicode.com/users")
.then((response) => response.json())
.then((result) => {
result.forEach((element) => {
sampleEle.innerHTML += element.username + "<br>";
});
})
.catch((err) => alert(err));
});
</script>
</body>
</html>输出
单击“单击此处”按钮后 −
更新于： 11-May-2020
786 次浏览
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