Improve code style

Author: tshemsedinov

JavaScript/1-callback.js

@@ -18,5 +18,6 @@ sum(2, 3, (res) => {
 const total = (a, b, callback) => callback(null, a + b);
 
 total(2, 3, (error, res) => {
+  if (error) console.error(error);
   console.log(`sum(2, 3) = ${res}`);
 });

JavaScript/2-callback-use.js

@@ -32,6 +32,7 @@ const timer = setInterval(() => {
 const fs = require('node:fs');
 
 fs.readFile('./1-callback.js', 'utf8', (err, data) => {
+  if (err) console.error(err);
   console.log({ lines: data.split('\n').length });
 });
 

JavaScript/3-callback-named.js

@@ -17,6 +17,7 @@ const fs = require('node:fs');
 
 {
   const print = (file) => (err, data) => {
+    if (err) console.error(err);
     console.log({ file, lines: data.split('\n').length });
   };
 

JavaScript/Tasks/5-errors.js

@@ -30,12 +30,13 @@ const calculateSubtotal = (goods, callback) => {
 const calculateTotal = (order, callback) => {
   const expenses = new Map();
   let total = 0;
+  const calc = (groupName) => (amount) => {
+    total += amount;
+    expenses.set(groupName, amount);
+  };
   for (const groupName in order) {
     const goods = order[groupName];
-    calculateSubtotal(goods, (amount) => {
-      total += amount;
-      expenses.set(groupName, amount);
-    });
+    calculateSubtotal(goods, calc(groupName));
     if (total > MAX_PURCHASE) {
       throw new Error('Total is above the limit');
     }

JavaScript/b-errors.js

@@ -37,7 +37,7 @@ try {
   a1(75);
   a1(100);
   a1(-200)(50)(30);
-} catch (e) {
+} catch {
   console.log('Never');
 }
 

JavaScript/c-hell.js

@@ -30,13 +30,18 @@ const writeReport = (path, data, callback) => {
 // Callback hell example
 
 readConfig('config.json', (error, config) => {
+  if (error) console.error(error);
   const min = config.population.minimalLimit;
   const sql = `select * from cities where size > ${min}`;
   selectFromDb(sql, (error, cities) => {
+    if (error) console.error(error);
     const url = 'http://domain.name/api';
     apiRequest(url, cities, (error, stats) => {
+      if (error) console.error(error);
       generateReport(cities, stats, (error, data) => {
+        if (error) console.error(error);
         writeReport('README.md', data, (error, res) => {
+          if (error) console.error(error);
           if (res.success) console.log('All done!');
         });
       });