tessl/npm-response-time
Response time middleware for Node.js servers that measures and reports HTTP request duration
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Response Time
Response Time is a Node.js middleware library that measures and reports HTTP request response times. It creates middleware that records the elapsed time from when a request enters the middleware to when the response headers are written out to the client.
Package Information
- Package Name: response-time
- Package Type: npm
- Language: JavaScript
- Installation:
npm install response-time
Core Imports
const responseTime = require('response-time');Basic Usage
const express = require('express');
const responseTime = require('response-time');
const app = express();
// Add X-Response-Time header automatically
app.use(responseTime());
app.get('/', (req, res) => {
res.send('hello, world!');
});
app.listen(3000);Capabilities
Automatic Header Mode
Creates middleware that automatically adds an X-Response-Time header to responses.
/**
* Create middleware that adds X-Response-Time header displaying response duration
* @param {ResponseTimeOptions} [options] - Configuration options
* @returns {Function} Express/Connect middleware function
*/
function responseTime(options?: ResponseTimeOptions): MiddlewareFunction;Usage Examples:
const express = require('express');
const responseTime = require('response-time');
const app = express();
// Default options (3 digits, X-Response-Time header, ms suffix)
app.use(responseTime());
// Custom precision
app.use(responseTime({ digits: 5 }));
// Custom header name
app.use(responseTime({ header: 'X-Time-Taken' }));
// No suffix
app.use(responseTime({ suffix: false }));
// Combined options
app.use(responseTime({
digits: 2,
header: 'X-Processing-Time',
suffix: true
}));Custom Callback Mode
Creates middleware that measures response time and calls a custom function with the timing data.
/**
* Create middleware that records response time and calls custom callback
* @param {ResponseTimeCallback} fn - Callback function receiving timing data
* @returns {Function} Express/Connect middleware function
*/
function responseTime(fn: ResponseTimeCallback): MiddlewareFunction;Usage Examples:
const express = require('express');
const responseTime = require('response-time');
const StatsD = require('node-statsd');
const app = express();
const stats = new StatsD();
// Custom metrics collection
app.use(responseTime((req, res, time) => {
const stat = (req.method + req.url).toLowerCase()
.replace(/[:.]/g, '')
.replace(/\//g, '_');
stats.timing(stat, time);
}));
// Logging response times
app.use(responseTime((req, res, time) => {
console.log(`${req.method} ${req.url} - ${time}ms`);
}));
// Conditional processing
app.use(responseTime((req, res, time) => {
if (time > 1000) {
console.warn(`Slow request: ${req.method} ${req.url} took ${time}ms`);
}
}));Vanilla HTTP Server Usage
Response-time can be used with vanilla Node.js HTTP servers without Express.
Usage Example:
const http = require('http');
const finalhandler = require('finalhandler');
const responseTime = require('response-time');
// Create middleware instance
const _responseTime = responseTime();
http.createServer((req, res) => {
const done = finalhandler(req, res);
_responseTime(req, res, (err) => {
if (err) return done(err);
// Respond to request
res.setHeader('content-type', 'text/plain');
res.end('hello, world!');
});
}).listen(3000);Types
/**
* Configuration options for automatic header mode
*/
interface ResponseTimeOptions {
/** Number of decimal digits in output (default: 3) */
digits?: number;
/** Name of response header to set (default: 'X-Response-Time') */
header?: string;
/** Whether to add 'ms' suffix to output (default: true) */
suffix?: boolean;
}
/**
* Callback function for custom response time handling
* @param req - HTTP request object
* @param res - HTTP response object
* @param time - Response time in milliseconds
*/
type ResponseTimeCallback = (req: any, res: any, time: number) => void;
/**
* Express/Connect middleware function signature
* @param req - HTTP request object
* @param res - HTTP response object
* @param next - Next middleware function
*/
type MiddlewareFunction = (req: any, res: any, next: Function) => void;Backward Compatibility
The library supports a deprecated single number argument for backwards compatibility:
// Deprecated - triggers deprecation warning
app.use(responseTime(3));
// Equivalent modern usage
app.use(responseTime({ digits: 3 }));Error Handling
Response-time follows standard Express middleware error handling patterns. If an error occurs, it will be passed to the next middleware via the next(err) function.
Integration Patterns
Express Application
const express = require('express');
const responseTime = require('response-time');
const app = express();
// Apply to all routes
app.use(responseTime());
app.get('/api/users', (req, res) => {
// Your route logic
res.json({ users: [] });
});Connect Application
const connect = require('connect');
const responseTime = require('response-time');
const app = connect();
app.use(responseTime());
app.use((req, res) => {
res.end('Hello World');
});- Workspace
- tessl
- Visibility
- Public
- Created
- Last updated
- Describes
- Publish Source
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