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See demo at

Display and compare biological maps (genetic, physical, cytogenetic, genomic; linkage groups, chromosomes, scaffolds).


General Setup

Prerequisite: npm is required so install NodeJs if you do not have it. npm is used as javascript package manager and task runner here.

  • Clone the project and initialize git submodule(s):
     git clone
     cd cmap-js
     git submodule init
     git submodule update
  • Install the required javascript packages listed in package.json / package-lock.json
    npm ci

Dev Container (VS Code and GitHub Codespaces)

VS Code or GitHub Codespace users can use a Dev Container to simplify setup for cmap-js (see additional instructions for setting up VS Code to use dev containers).

After opening the respository in a dev container (VS Code: first run Clone Repository), issue the following command to install required javascript packages:

npm ci

Potential Issues

There has been a report of node getting stuck during install on macOS. This is not a cmap-js issue, but should be fixable following the directions found here.

Build and Tests

ES6 code is transpiled with Babel and bundled with Rollup, and the results are written into the build/ directory. Here are some of the available scripts:

npm run lint     # run linter only
npm run build    # linter and rollup, babel (set NODE_ENV=production to minify)
npm run test     # mocha test runner
npm run coverage # mocha and istanbul coverage report
npm run watch    # build, watch and livereload

Watch script has only been tested on macOS systems, and may not work on other platforms.

Configuration File

The cmap.json file has configuration parameters such as data sources, page header, and data attribution, etc. The javascript app will fetch cmap.json from the root of the server. The format of cmap.json is specified in cmap-schema.json. You can test your config file versus the schema with:

npm run validate-config  # run ajv to validate cmap-schema.json with cmap.json


Clicking on a marker or a QTL region will bring up a popup with more information about whatever is clicked on. This may have one-or-more features if density is high enough.

Clicking on the aqua position bar and dragging will pan the current backbone position if you are zoomed in at all.

If you click-and-drag, a box will appear. Ending the drag will have two different behaviors, depending on the selected area.

If the position bar isn't included in the selected area, a popup will appear with all the elements that occur in selected region.

If the position bar is included in the selected area, the view will zoom to the selected region.

Zoom may also adjusted by using the mouse wheel, similar to Google Maps.

Using the white boxes with arrows at the top of a map swaps map position with its neighbor. Maps may be added and removed from display using the as labeled buttons.

URL Control

You can override which maps are displayed initally using a query string of the form:


Having an empty query string, or not providing any views will cause cmap to display the default initial view, otherwise cmap will attempt to match the map by name, and then display matches in order.

Any name that is duplicated will default to the first match. The displayed view will match the configuration for that specific map, not the view defined in the initialView section of the configuration.

More robust query string control of the view will be added as development continues.

Known Issues

  • Manhattan style plots can not be added through the configure/add track menu.
  • Configuration menu will not display configuration of current tracks, however tracks may still be configured in the same way as in the cmap.json, overwriting existing tracks.


Display and compare biological maps (genetic, physical, cytogenetic, genomic, linkage groups, chromosomes, scaffolds).