HowProgrammingWorks
diff --git a/‎JavaScript/Tasks/5-errors.js
Copy file name to clipboard
+66Lines changed: 66 additions & 0 deletions b/‎JavaScript/Tasks/5-errors.js
Copy file name to clipboard
+66Lines changed: 66 additions & 0 deletions
@@ -0,0 +1,66 @@
+'use strict';
+
+// Task: rewrite error handling to use callback-last-error-first
+// contract to return errors instead of throwing them.
+// So remove all try/catch blocks and pass errors to callbacks.
+// Hint: You may also use error.cause to wrap escalated errors.
+// Extra credit task: use AggregateError to combine escalated errors.
+// Extra credit task: fix eslint error: "Function declared in a loop
+//   contains unsafe references to variable(s) 'total'  no-loop-func"
+
+const MAX_PURCHASE = 2000;
+
+const calculateSubtotal = (goods, callback) => {
+  let amount = 0;
+  for (const item of goods) {
+    if (typeof item.name !== 'string') {
+      throw new Error('Noname in item in the bill');
+    }
+    if (typeof item.price !== 'number') {
+      throw new Error(`${item.name} price expected to be number`);
+    }
+    if (item.price < 0) {
+      throw new Error(`Negative price for ${item.name}`);
+    }
+    amount += item.price;
+  }
+  callback(amount);
+};
+
+const calculateTotal = (order, callback) => {
+  const expenses = new Map();
+  let total = 0;
+  for (const groupName in order) {
+    const goods = order[groupName];
+    calculateSubtotal(goods, (amount) => {
+      total += amount;
+      expenses.set(groupName, amount);
+    });
+    if (total > MAX_PURCHASE) {
+      throw new Error('Total is above the limit');
+    }
+  }
+  return callback({ total, expenses });
+};
+
+const purchase = {
+  Electronics: [
+    { name: 'Laptop', price: 1500 },
+    { name: 'Keyboard', price: 100 },
+    { name: 'HDMI cable' },
+  ],
+  Textile: [
+    { name: 'Bag', price: 50 },
+    { price: 20 },
+  ],
+};
+
+try {
+  console.log(purchase);
+  calculateTotal(purchase, (bill) => {
+    console.log(bill);
+  });
+} catch (error) {
+  console.log('Error detected');
+  console.error(error);
+}