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# Code Snippet: [Title of Snippet] ## Description [Provide a brief description of what this code does and why it's useful] ## Language/Environment - **Language**: [e.g., JavaScript, Python, Java] - **Version**: [e.g., Python 3.9, Node.js 16.x] - **Framework/Library**: [e.g., React, Django] (if applicable) ## Dependencies ``` [List any libraries, packages, or dependencies required] # For example, for Python: # requests==2.26.0 # pandas==1.3.3 ``` ## Code ```[language] [Your code here] ``` ## Usage Example ```[language] [Example of how to use this code] ``` ## Expected Output ``` [What the code is expected to output when run] ``` ## Explanation [Provide a step-by-step explanation of how the code works] 1. [Step 1] 2. [Step 2] 3. [Step 3] ## Edge Cases & Limitations - [List any known limitations] - [Describe edge cases or scenarios where this might not work] - [Performance considerations] ## Alternative Approaches [If there are other ways to solve the same problem, briefly mention them] ## Additional Notes [Any other relevant information] ## References - [Link to relevant documentation] - [Link to related resources] - [Credit original sources if applicable] --- Author: [Your Name] Last Updated: [YYYY-MM-DD]
A middleware function for Express.js that implements a basic rate limiter using in-memory storage.
// Simple rate limiter middleware for Express.js
const rateLimit = (options = {}) => {
const {
windowMs = 60 * 1000, // 1 minute by default
max = 100, // max 100 requests per windowMs
message = 'Too many requests, please try again later.'
} = options;
// Store for tracking requests
const requestStore = new Map();
// Cleanup old entries every windowMs
setInterval(() => {
const now = Date.now();
requestStore.forEach((timestamp, key) => {
if (now - timestamp > windowMs) {
requestStore.delete(key);
}
});
}, windowMs);
return (req, res, next) => {
const key = req.ip || req.headers['x-forwarded-for'] || 'unknown';
const now = Date.now();
// Initialize counter for this IP if it doesn't exist
if (!requestStore.has(key)) {
requestStore.set(key, { count: 1, resetAt: now + windowMs });
return next();
}
const client = requestStore.get(key);
// Reset count if window has passed
if (now > client.resetAt) {
client.count = 1;
client.resetAt = now + windowMs;
return next();
}
// Increment count and check against max
client.count++;
if (client.count > max) {
return res.status(429).send(message);
}
return next();
};
};