Code Sample 1

This is the JavaScript code for 08_10 in the exercise files.

Callback Function

	/**
	 * Using a callback function.
	 * @link https://developer.mozilla.org/en-US/docs/Glossary/Callback_function
	 */

	// Helper function to format currency numbers. Used by tipCalculator
	const formatter = (locale = "en-US", currency = "USD", value) => {
	  let formattedValue = new Intl.NumberFormat(locale, {
		style: "currency",
		currency: currency,
	  }).format(value);

	  return formattedValue;
	};

	// Callback receives finalTip object, creates and outputs table on the DOM.
	const printHTML = (finalTip) => {
	  const tipTable = document.createElement("table");
	  tipTable.innerHTML = `
		<tr>
		  <td>Sum before tip:</td>
		  <td>${finalTip.sum}</td>
		</tr>
		<tr>
		  <td>Tip percentage:</td>
		  <td>${finalTip.percentage}</td>
		</tr>
		<tr>
		  <td>Tip:</td>
		  <td>${finalTip.tip}</td>
		</tr>
		<tr>
		  <td>Total:</td>
		  <td>${finalTip.total}</td>
		</tr>
	  `;
	  document.querySelector("main").append(tipTable);
	};

	// Create a finalTip object with all the data. Send it to the printHTML callback.
	const tipCalculator = (sum, percentage, locale, currency) => {
	  let tip = sum * (percentage / 100);
	  let total = sum + tip;

	  const finalTip = {
		sum: formatter(locale, currency, sum),
		percentage: percentage + "%",
		tip: formatter(locale, currency, tip),
		total: formatter(locale, currency, total),
	  };
	};

	tipCalculator(29.95, 18, "de-DE", "EUR");