Express Instruments

A library that provides middleware functions to measure aspects of the request/response cycle in express.js app.

Install

npm install express-instruments

Usage

responseTime

Measures response time which can be accessed on the response object as res.responseTime.

var express = require('express');
var instruments = require('express-instruments');

app = express();

app.use(instruments.responseTime());

app.use(function(req, res, next) {
    var handler = function() {
        res.removeListener('finish', handler);
        console.log('response time was:', res.responseTime);
    };
    res.on('finish', handler);
    next():
});

stopwatch

Provides a means to measure time intervals during request handling.

var express = require('express');
var instruments = require('express-instruments');
var Product = require('./lib/products/models/Product');

app = express();

app.use(instruments.stopwatch());

app.get(function(req, res) {
    Product.find({type: 'book'}, req.mark('fetch', function(err, res) {
        console.log('printing interval marks:');
        console.log(req.marks);
    });

    // another way to use it
    req.mark('timeout');
    setTimeout(function() {
        req.mark('timeout');
    }, 2000);

    // and yet another
    var probe = req.mark('timeout');
    setTimeout(probe, 2000);
});