Understand the five caching mechanism implementation methods of JavaScript

In-depth understanding: Five implementation methods of JS caching mechanism, specific code examples are required

Introduction:
In front-end development, the caching mechanism is to optimize web page performance one of the important means. Through reasonable caching strategies, requests to the server can be reduced and user experience improved. This article will introduce the implementation of five common JS caching mechanisms, with specific code examples so that readers can better understand and apply them.

1. Variable caching
Variable caching is the most basic and simplest caching method. By storing the results of one-time calculations in variables, repeated calculations are avoided and operating efficiency is improved.

Code example:

function calculate() {
  var result = 0; // 将计算结果存储在 result 变量中
  // 复杂的计算逻辑
  return result;
}

var cachedValue = calculate(); // 第一次计算并缓存结果
console.log(cachedValue);

// 后续使用缓存结果
console.log(cachedValue);
console.log(cachedValue);

2. Local storage cache
The local storage cache saves the data in the browser’s local storage and reads the local storage directly the next time the data is obtained. There is no need to request the server again, which can reduce network transmission time.

Code example:

// 存储数据
localStorage.setItem('key', 'value');

// 获取数据
var cachedValue = localStorage.getItem('key');
console.log(cachedValue);

3. Memory cache
Memory cache saves data in memory and can be read quickly, but it is only valid on the current page and will be refreshed after the page is refreshed. Empty.

Code example:

var cache = {}; // 使用对象作为缓存容器

// 存储数据
cache['key'] = 'value';

// 获取数据
var cachedValue = cache['key'];
console.log(cachedValue);

4. HTTP caching
HTTP caching is implemented by setting the Cache-Control and Expires fields in the response header, which allows the browser to cache the requested resources. , the cached resource will be returned directly when requested again.

Code example:

// 设置响应头
res.setHeader('Cache-Control', 'max-age=3600'); // 设置缓存有效期为1小时
res.setHeader('Expires', new Date(Date.now() + 3600000).toUTCString());

// 后续请求将直接返回缓存的资源

5. CDN caching
CDN caching publishes static resources to CDN nodes and quickly responds to requests through nodes close to users to reduce server pressure.

Code sample: None

Conclusion:
The above introduces the five implementation methods of JS caching mechanism, including variable caching, local storage caching, memory caching, HTTP caching and CDN caching. Different caching methods are suitable for different scenarios. Developers can choose appropriate caching strategies according to actual needs to optimize web page performance and improve user experience. However, it should be noted that the caching mechanism may cause data consistency and update problems, so you need to consider carefully when using caching.

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