From fa2d5d81a69d11eeabc1e11f9465c35fe7e2db60 Mon Sep 17 00:00:00 2001
From: PinkR1ver <3180102330@zju.edu.cn>
Date: Wed, 27 Mar 2024 20:44:24 +0800
Subject: [PATCH] Add note

---
 .../coding_knowledge/coding_lang_MOC.md       |   1 +
 .../coding_knowledge/js/proxy_in_js.md        | 116 ++++++++++++++++++
 2 files changed, 117 insertions(+)
 create mode 100644 content/computer_sci/coding_knowledge/js/proxy_in_js.md

diff --git a/content/computer_sci/coding_knowledge/coding_lang_MOC.md b/content/computer_sci/coding_knowledge/coding_lang_MOC.md
index 3d902a146..1fb8960b3 100644
--- a/content/computer_sci/coding_knowledge/coding_lang_MOC.md
+++ b/content/computer_sci/coding_knowledge/coding_lang_MOC.md
@@ -31,4 +31,5 @@ date: 2024-03-27
 
 * [DOM](computer_sci/coding_knowledge/js/DOM.md)
 * [TypeScript vs. JavaScript](computer_sci/coding_knowledge/js/TypeScript_vs_JavaScript.md)
+* [Proxy in JS](computer_sci/coding_knowledge/js/proxy_in_js.md)
 
diff --git a/content/computer_sci/coding_knowledge/js/proxy_in_js.md b/content/computer_sci/coding_knowledge/js/proxy_in_js.md
new file mode 100644
index 000000000..0e057f2a1
--- /dev/null
+++ b/content/computer_sci/coding_knowledge/js/proxy_in_js.md
@@ -0,0 +1,116 @@
+---
+title: Proxy in JavaScript
+tags:
+  - coding-language
+  - javascript
+date: 2024-03-27
+---
+
+# Intro
+
+**Proxy** 对象用于创建一个对象的代理，**从而实现基本操作的拦截和自定义**（如属性查找、赋值、枚举、函数调用等）。
+
+使用 `Proxy()` 构造函数来创建一个新的 Proxy 对象。 构造函数接收两个必须的参数：
+
+- **target**：要创建代理的对象（可以是任何类型的对象，包括原生数组，函数，甚至另一个代理）。
+- **handler**：定义了代理的自定义行为的对象。
+
+
+# Example
+
+
+```js
+const target = {
+  name: "John Doe",
+  age: 30,
+};
+
+const handler = {
+  get: function(target, property) {
+    console.log(`Getting property "${property}" from target`);
+    return Reflect.get(target, property);
+  },
+  set: function(target, property, value) {
+    console.log(`Setting property "${property}" to "${value}" on target`);
+    return Reflect.set(target, property, value);
+  },
+};
+
+const proxy = new Proxy(target, handler);
+```
+
+**拦截操作**
+
+`handler` 对象可以包含以下属性，用于拦截对代理对象的各种操作：
+
+- **get**：拦截属性读取操作。
+- **set**：拦截属性赋值操作。
+- **has**：拦截 `in` 操作。
+- **deleteProperty**：拦截 `delete` 操作。
+- **apply**：拦截函数调用操作。
+- **construct**：拦截构造函数调用操作。
+- **getOwnPropertyDescriptor**：拦截 `Object.getOwnPropertyDescriptor` 操作。
+- **defineProperty**：拦截 `Object.defineProperty` 操作。
+- **preventExtensions**：拦截 `Object.preventExtensions` 操作。
+- **isExtensible**：拦截 `Object.isExtensible` 操作。
+- **ownKeys**：拦截 `Object.getOwnPropertyNames` 和 `Object.getOwnPropertySymbols` 操作。
+
+# Demo
+
+## 数据验证
+
+```js
+const handler = {
+  set: function(target, property, value) {
+    if (typeof value !== "number") {
+      throw new Error("Invalid value: " + value);
+    }
+
+    return Reflect.set(target, property, value);
+  },
+};
+
+const proxy = new Proxy({}, handler);
+
+proxy.age = 30; // 成功
+proxy.name = "John Doe"; // 抛出错误
+```
+
+## 数据格式化
+
+```js
+const handler = {
+  get: function(target, property) {
+    const value = Reflect.get(target, property);
+    if (property === "name") {
+      return value.toUpperCase();
+    }
+
+    return value;
+  },
+};
+
+const proxy = new Proxy({ name: "John Doe" }, handler);
+
+console.log(proxy.name); // 输出 "JOHN DOE"
+```
+
+## 权限控制
+
+
+```js
+const handler = {
+  get: function(target, property) {
+    if (currentUser.hasPermission(property)) {
+      return Reflect.get(target, property);
+    }
+
+    return undefined;
+  },
+};
+
+const proxy = new Proxy(user, handler);
+
+console.log(proxy.age); // 成功
+console.log(proxy.salary); // undefined
+```