README.md

Measured.js

A thin wrapper around the Node.js Performance API to transparently measure the execution time of asynchronous functions.

Installing

Using yarn:

yarn add @twuni/measured

Using npm:

npm install @twuni/measured

Usage

First, import the module:

// Using ES6 modules:
import { measured } from '@twuni/measured';

// ...or, if you are using CommonJS modules:
const { measured } = require('@twuni/measured');

Then, you can use the measured() function like this:

If this is what your code looked like before:

await doExpensiveThing();

To measure that, just change it to read something like this:

await measured(doExpensiveThing, {
  onComplete: ({ duration }) => {
    console.debug(`Completed in ${duration}ms`);
  },

  onReject: ({ duration }) => {
    console.debug(`Rejected in ${duration}ms`);
  },

  onResolve: ({ duration }) => {
    console.debug(`Resolved in ${duration}ms`);
  }
})();

Each of these callbacks is optional and is described as follows:

• The #onComplete() function will run whether the wrapped behavior resolves or rejects.

• The #onResolve() function will run only when the wrapped behavior resolves.

• The #onReject() function will run only when the wrapped behavior rejects.

Examples

Express.js Middleware

const express = require('express');
const app = express();

app.use((request, response, next) => measured(next, {
  onComplete: ({ duration }) => {
    console.log(`${request.method} ${request.path} served in ${duration}ms`);
  }
})());