docparse-dumpinvoices/lib/getSalesTaxCostValue.js

takes a list of couchdb invoice ids and exports the data contained within those invoices to an Excel spreadsheet

var num = require('num')
var pattern = /sales tax/i
module.exports = function (costs) {
  var salesTaxCosts = costs.filter(function (cost) {
    var description = cost.description
    return pattern.test(description)
    var value = cost.value
  })

  var total = salesTaxCosts.reduce(function (a, b) {
    return a.add(b.value)
  }, num(0)).toString()
  return total
}