README

[inverse-tax] / tax_ui.js

"use strict";

function load_tax_table(table_id, deductible_id = null) {
  const deductible = deductible_id == null ? 0.0 : parseFloat(document.getElementById(deductible_id).value);
  return apply_deductible(parse_tax_table(document.getElementById(table_id).value), deductible);
}

function format_number(n) {
  return n.toLocaleString('en', {useGrouping:true, style: 'currency', currency: 'USD'});
}

function calculate() {
  const tax_tables = [
    load_tax_table('tax_table_1', 'deductible_1'),
    load_tax_table('tax_table_2', 'deductible_2'),
    load_tax_table('tax_table_3'),
    load_tax_table('tax_table_4'),
    load_tax_table('tax_table_5')
  ];
  const after_tax = parseFloat(document.getElementById('after_tax').value);

  const merged_tax_table = tax_tables.reduce(merge_tax_tables);
  const before_tax = invert(merged_tax_table)(after_tax);
  const taxes = tax_tables.map(t => tax(t, before_tax));

  document.getElementById('before_tax').textContent = format_number(before_tax);
  document.getElementById('tax_1').textContent = format_number(taxes[0]);
  document.getElementById('tax_2').textContent = format_number(taxes[1]);
  document.getElementById('tax_3').textContent = format_number(taxes[2]);
  document.getElementById('tax_4').textContent = format_number(taxes[3]);
  document.getElementById('tax_5').textContent = format_number(taxes[4]);
  document.getElementById('after_tax_verification').textContent = format_number(before_tax - sum(taxes));
}