winnow/lib/filter-and-transform/transforms/reduce-precision.js

Apply sql-like filters to GeoJSON

const transformCoordinates = require('../../helpers/transform-coordinates')

module.exports = function (geometry, precision) {
  if (!geometry) return

  const { type, coordinates } = geometry

  if (!coordinates) return geometry

  return {
    type,
    coordinates: reducePrecision(coordinates, precision)
  }
}

function reducePrecision (coordinates, precision) {
  return transformCoordinates(coordinates, { precision }, (coordinates, { precision }) => {
    return coordinates.map(position => {
      return parseFloat(position.toFixed(precision))
    })
  })
}