grunt-topojson

Convert GeoJSON to TopoJSON

Getting Started

This plugin requires Grunt ~0.4.4

If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:

npm install grunt-topojson --save-dev

Once the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:

grunt.loadNpmTasks('grunt-topojson');

The "topojson" task

Overview

In your project's Gruntfile, add a section named topojson to the data object passed into grunt.initConfig().

grunt.initConfig({
  topojson: {
    options: {
      // Task-specific options go here.
    },
    your_target: {
      // Target-specific file lists and/or options go here.
    },
  },
});

Options

options.idProperty

Type: String Default value: null

The key from geography.properties that should be used as id. Defaults to the geography.id.

options.copyProperties

Type: Array Default value: null

An array of properties to be copied. Use an empty array to not copy any properties. Keep null to copy all properties.

options.collectionName

Type: String Default value: null

A property to be used to name the collection. Defaults to task name. For example, if your config looks like this:

topojson: {
  world: {
    files: []
  }
}

The collectionName will default to world. This can be overridden by specifying a collectionName.

topojson: {
  world: {
    files: []
  },
  options: {
    collectionName: 'custom-data-world'
  }
}

All other options can be found on the TopoJSON API documentation page

Usage Examples

Default Options

With all default options, src/world.json will be converted into topoJSON and placed in dest/world.topo.json. The results will look something like:

{"type":"Topology","objects":{"world":{"type":"GeometryCollection","geometries":[{"type":"Polygo...

grunt.initConfig({
  topojson: {
    world: {
      options: {},
      files: {
        'dest/world.topo.json': ['src/world.json'],
      }
    }
  },
});

Custom Options

In this example, custom options are used to do something else with whatever else. So if the testing file has the content Testing and the 123 file had the content 1 2 3, the generated result in this case would be Testing: 1 2 3 !!!

{"type":"Topology","objects":{"custom-world":{"type":"GeometryCollection","geometries":[{"type":"Polygo...

grunt.initConfig({
  topojson: {
    world: {
      options: {
        collectionName: 'custom-world',
        quantization: 1e7
      },
      files: {
        'dest/world.topo.json': ['src/world.json'],
      }
    }
  },
});

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.

Release History

(Nothing yet)