v1.6.21

• Source files are now ES6 modules. The UMD bundle is built by Rollup.
• Tests are now implemented using Tape.
• Updated dependencies.
• Note to Bower users: you may need to bower cache clean before installing.

v1.6.20

• Fix accidental global n in topojson.merge.

1.6.19

• Document -- for separating input files from options.

1.6.18

• Workaround optimization bug in Chrome/V8 for topojson.presimplify.

1.6.17

• Fix --simplify-proportion calculation.

1.6.16

• Fix --simplify-proportion crash.

1.6.15

• Simplification now operates on each arc independently, improving performance.
• The topojson-group command-line tool now supports grouping Point and MultiPoint geometries.
• Better support for Browserify.

1.6.14

• Fix bug joining with external properties using the default “id” column as primary key.

1.6.13

• Fix topojson-svg error when an output filename is specified.

1.6.11

• The --id-property argument may now take a JavaScript expression defining how to compute the id from input properties. For example, this can be used to concatenate multiple input properties into the id.
• The --properties argument likewise now accepts JavaScript expressions to compute output properties from input properties. For example, this can be used to coerce strings to numbers or to split a single input property into multiple output properties.
• Because properties are now defined as expressions, the syntax for properties that are not JavaScript identifiers have changed slightly. For example, whereas before you could specify the property "Estimate; Total" as --properties=+'Estimate; Total', now you must say --properties='+d.properties["Estimate; Total"]'.