什么是 JavaScript 中的闭包?

javascriptweb developmentobject oriented programming更新于 2025/8/30 0:44:17

JavaScript 中的闭包允许我们从内部函数访问外部函数作用域，即使外部函数已执行并返回。这意味着内部函数将始终可以访问外部函数变量。

以下是 JavaScript 中闭包的代码 −

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>JavaScript Closures</h1>
<div style="color: green;" class="result"></div>
<button class="btn">点击此处</button>
<h3>Click on the above button to add two numbers using closure</h3>
<script>
   let sampleEle = document.querySelector(".sample");
   let resEle = document.querySelector(".result");
   function add(num) {
      return function add1(num1) {
         resEle.innerHTML += `${num}+${num1} = ${num + num1}`;
      };
   }
   document.querySelector(".Btn").addEventListener("click", () => {
      let storeadd = add(99);
      storeadd(44);
   });
</script>
</body>
</html>