Number and Currency Formatting

/**
 * Get device's number formatting settings
 * @returns Object containing decimal and grouping separators
 */
function getNumberFormatSettings(): NumberFormatSettings;

interface NumberFormatSettings {
  /** Character used for decimal separation (e.g., ".", ",") */
  decimalSeparator: string;
  /** Character used for thousands grouping (e.g., ",", ".", " ") */
  groupingSeparator: string;
}

import { getNumberFormatSettings } from "react-native-localize";

const formatSettings = getNumberFormatSettings();
console.log(formatSettings);
// US: { decimalSeparator: ".", groupingSeparator: "," }
// DE: { decimalSeparator: ",", groupingSeparator: "." }
// FR: { decimalSeparator: ",", groupingSeparator: " " }

// Format numbers according to device preferences
function formatNumber(value: number): string {
  const { decimalSeparator, groupingSeparator } = getNumberFormatSettings();
  
  // Use native toLocaleString for proper formatting
  return value.toLocaleString(undefined, {
    minimumFractionDigits: 2,
    maximumFractionDigits: 2
  });
}

console.log(formatNumber(1234.56));
// US: "1,234.56"
// DE: "1.234,56"
// FR: "1 234,56"

import { getNumberFormatSettings } from "react-native-localize";

function formatCurrency(amount: number, currencyCode: string): string {
  const { decimalSeparator, groupingSeparator } = getNumberFormatSettings();
  
  // Manual formatting using device separators
  const parts = Math.abs(amount).toFixed(2).split('.');
  const integerPart = parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, groupingSeparator);
  const decimalPart = parts[1];
  
  const formatted = `${integerPart}${decimalSeparator}${decimalPart}`;
  const sign = amount < 0 ? '-' : '';
  
  return `${sign}${currencyCode} ${formatted}`;
}

console.log(formatCurrency(1234.56, "USD"));
// US: "USD 1,234.56"
// DE: "USD 1.234,56"

/**
 * Get currencies associated with device locales
 * @returns Array of ISO currency codes (e.g., ["USD", "EUR"])
 */
function getCurrencies(): string[];

import { getCurrencies, getCountry } from "react-native-localize";

const currencies = getCurrencies();
console.log(currencies); // ["USD", "EUR"]

// Get primary currency
const primaryCurrency = currencies[0];
console.log(primaryCurrency); // "USD"

// Use for currency selection
function getDefaultCurrency(): string {
  const currencies = getCurrencies();
  return currencies[0] || "USD"; // fallback to USD
}

// Currency-aware price formatting
function formatPrice(amount: number): string {
  const currency = getDefaultCurrency();
  
  return new Intl.NumberFormat(undefined, {
    style: 'currency',
    currency: currency
  }).format(amount);
}

console.log(formatPrice(29.99));
// US: "$29.99"
// EU: "29,99 €"
// UK: "£29.99"

import { getCurrencies, getCountry } from "react-native-localize";

// App with multi-currency support
function getSupportedCurrencies(): string[] {
  const deviceCurrencies = getCurrencies();
  const appSupportedCurrencies = ["USD", "EUR", "GBP", "JPY", "CAD"];
  
  // Find intersection of device and app currencies
  return deviceCurrencies.filter(currency => 
    appSupportedCurrencies.includes(currency)
  );
}

// Currency selection with fallback
function selectBestCurrency(): string {
  const supported = getSupportedCurrencies();
  if (supported.length > 0) {
    return supported[0];
  }
  
  // Fallback based on country
  const country = getCountry();
  const countryToCurrency = {
    "US": "USD",
    "GB": "GBP", 
    "JP": "JPY",
    "CA": "CAD"
  };
  
  return countryToCurrency[country] || "USD";
}

import { getCurrencies, getNumberFormatSettings } from "react-native-localize";

class PriceFormatter {
  private currency: string;
  private formatSettings: NumberFormatSettings;
  
  constructor() {
    this.currency = getCurrencies()[0] || "USD";
    this.formatSettings = getNumberFormatSettings();
  }
  
  formatPrice(amount: number, showCurrency: boolean = true): string {
    const formatted = new Intl.NumberFormat(undefined, {
      style: showCurrency ? 'currency' : 'decimal',
      currency: this.currency,
      minimumFractionDigits: 2,
      maximumFractionDigits: 2
    }).format(amount);
    
    return formatted;
  }
  
  formatDiscount(original: number, discounted: number): string {
    const savings = original - discounted;
    const percentage = Math.round((savings / original) * 100);
    
    return `Save ${this.formatPrice(savings)} (${percentage}%)`;
  }
}

const formatter = new PriceFormatter();
console.log(formatter.formatPrice(99.99)); // "$99.99" or "99,99 €"
console.log(formatter.formatDiscount(99.99, 79.99)); // "Save $20.00 (20%)"