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A general purpose, real-time visualization library.

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By Ryan Sandor Richards

Build Status Dependency Status devDependency Status

Epoch is a general purpose charting library for application developers and visualization designers. It focuses on two different aspects of visualization programming: basic charts for creating historical reports, and real-time charts for displaying frequently updating timeseries data.

To get started using Epoch, please refer to the Epoch Project Site. There you can find full documentation and guides to help you start using Epoch right away.


Epoch can be easily installed via the following package managers:

If you don't see your favorite package manager in the list above feel free to open up an issue and let us know. Finally, you can download any release of the library from the project releases page.

Important: Epoch requires d3. In order to work properly your page must load d3 before epoch.

Public CDN URLs

If you don't want to host the files yourself, you can use jsDelivr to serve the files:

  1. Visit epoch page on jsDelvr.
  2. Copy the provided URL's and link to them in your project.

Developing Epoch

Developing Epoch is a reasonably straight forward process. In this section we'll cover the basic on how to develop Epoch by detailing common build task, exploring how the source is arranged, and finally show how to use rendering tests to aid development.

Configuring Development Environment

Epoch requires the following for development:

  1. Node.js (v4.1.1+)
  2. NPM (v2.1.0+)

Once both are installed on your machine you will need to run

npm install
from the repository's root directory in order to install the npm packages required to develop epoch.

Once you have installed the required npm packages you can use

gulp build
to fully rebuild the source (see more information about gulp tasks below).

Basic Development Process

The best way to start contributing to Epoch is to follow these steps:

  1. Change to the source directory for the project
  2. Run
    gulp watch
    to recompile the project after source files change
  3. Make changes in a source file (either in
  4. In a web browser open the
    and browse the rendering tests
  5. Use the rendering tests to see if your changes had the desired result
  6. Ensure unit tests with pass
    npm test


Epoch uses two types of testing to ensure that changes do not cause unintended side effects. The first, unit tests, ensure that the core functional components of the library work as expected. The second, rendering tests, allow you to ensure that charts and graphs are correctly rendered.

It is important to keep both unit test and rendering tests up-to-date! When developing, use the following guidelines:

  • When adding new features make sure to add new tests
  • When changing existing functionality, ensure that the appropriate both types of tests still pass
  • If you want to make a new type of chart, add a whole new test suite for that chart!

Keeping the tests current makes it easier for others to review your code and spot issues. Also, pull requests without appropriate testing will not be merged.

Gulp Tasks

Epoch uses gulp to perform various tasks. The

file defines the following tasks:
  • gulp clean
    - Cleans the
  • gulp build
    - Builds the CoffeeScript and Sass source into the
  • gulp watch
    - Starts a watch script to recompile CoffeeScript and Sass when any files change.

Source Structure

The directory structure for the Epoch project follows some basic guidelines, here's an overview of how it is structured:

dist/                  - Compiled JavaScript and CSS source
src/                   - Main source directory
  core/                - Core Epoch Library Files        - Library Utility Routines          - d3 Extensions      - Data formatters       - Base Chart Classes         - CSS Querying Engine
  adapters/            - 3rd Party Library Adapters (currently only jQuery)
  basic/               - Basic Chart Classes
  time/                - Real-time Chart Classes      - Options / Global Classes for Adapter Implementations         - Base Classes for Basic Charts          - Data Formatting         - Main source file, defines name spaces, etc.         - Data Model          - Base Classes for Real-Time Charts
sass/                  - Scss source for the default epoch stylesheet
  render/              - Rendering tests
    basic/             - Basic chart rendering tests
    real-time/         - Real-time rendering tests
  unit/                - Unit tests

Release Checklist

  • Run
    npm test
    and ensure all tests pass
  • Run
    npm version [major|minor|patch]
  • Run
    npm publish
  • Update with the changes since last release
  • Update the
    branch's library version in

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