Wise money rate crawler

wise_crawl.js

const fromCurrency = searchParams.get('from') || 'SGD';
    const toCurrency = searchParams.get('to') || 'VND';
    let response;
    async function getRate(fromCurrency, toCurrency) {
      // Fetch the exchange rate from Wise
      response = await fetch(`https://wise.com/gb/currency-converter/${fromCurrency.toLowerCase()}-to-${toCurrency.toLowerCase()}-rate?amount=1`);

      // Extract the exchange rate from the response
      const html = await response.text();

      function findString(target, str) {
        const index = str.indexOf(target);
        if (index === -1) {
          return -1;
        } else {
          return str.substring(index + target.length, index + target.length + 30);
        }
      }

      function extractNumber(str) {
        const numberRegex = /-?\d+(\.\d+)?/;
        const match = str.match(numberRegex);
        if (match) {
          return Number(match[0]);
        } else {
          return null;
        }
      }

      const est = findString(`text-success`, html);
      if (est === -1) {
        return null;
      }
      return extractNumber(est);
    }

    const r = await getRate(fromCurrency, toCurrency);
    if (!r) {
      return new Response(JSON.stringify({ error: true, code: response.status, statusText: response.statusText }), {
        code: response.status,
        statusText: response.statusText,
        headers: {'Content-Type': 'application/json'},
      })
    }
    return new Response(JSON.stringify({
      data: r
    }), {
      headers: {
        ...corsHeaders,
        'Content-Type': 'application/json',
      },
    })