Improve code style

Author: tshemsedinov

JavaScript/1-callbacks.js

@@ -3,11 +3,14 @@
 const fs = require('node:fs');
 
 fs.readFile('file1.txt', 'utf8', (err, data) => {
-  console.log(err || data.toString());
+  if (err) console.error(err);
+  else console.log({ data });
   fs.readFile('file2.txt', 'utf8', (err, data) => {
-    console.log(err || data.toString());
+    if (err) console.error(err);
+    else console.log({ data });
     fs.readFile('file3.txt', 'utf8', (err, data) => {
-      console.log(err || data.toString());
+      if (err) console.error(err);
+      else console.log({ data });
     });
   });
 });

JavaScript/4-catch.js

@@ -2,25 +2,22 @@
 
 const fs = require('node:fs');
 
-const readTextFile = (filename) => fs.promises.readFile(filename, 'utf8');
+const readTextFile = (filename) => (
+  fs.promises.readFile(filename, 'utf8')
+);
 
-readTextFile('file1-.txt')
-  .then(
-    (data) => {
-      console.dir({ file1: data });
-      return readTextFile('file2.txt');
-    },
-    (reason) => {
-      console.log('Cannot read file1.txt --- A');
-      console.log(reason);
-    }
-  )
-  .catch(
-    (reason) => {
-      console.log('Cannot read file1.txt --- B');
-      console.log(reason);
-    }
-  )
+readTextFile('file1.txt')
+  .then((data) => {
+    console.dir({ file1: data });
+    return readTextFile('file2.txt');
+  }, (reason) => {
+    console.log('Cannot read file1.txt --- A');
+    console.log(reason);
+  })
+  .catch((reason) => {
+    console.log('Cannot read file1.txt --- B');
+    console.log(reason);
+  })
   .then((data) => {
     console.dir({ file2: data });
     return readTextFile('file3.txt');

JavaScript/5-finally.js

@@ -2,9 +2,7 @@
 
 const fs = require('node:fs');
 
-const readTextFile = (filename) => fs.promises.readFile(filename, 'utf8');
-
-readTextFile('file1-.txt')
+fs.promises.readFile('file1.txt', 'utf8')
   .then((data) => {
     console.dir({ file1: data });
   })

JavaScript/8-all.js

@@ -7,7 +7,7 @@ const baseUrl = 'http://localhost:3000';
 const promises = [
   fetch(baseUrl + '/person'),
   fetch(baseUrl + '/'),
-  fetch(baseUrl + '/city')
+  fetch(baseUrl + '/city'),
 ];
 
 Promise.all(promises)

JavaScript/9-race.js

@@ -7,7 +7,7 @@ const baseUrl = 'http://localhost:3000';
 const promises = [
   fetch(baseUrl + '/person'),
   fetch(baseUrl + '/'),
-  fetch(baseUrl + '/city')
+  fetch(baseUrl + '/city'),
 ];
 
 Promise.race(promises)

JavaScript/a-thenable.js

@@ -3,27 +3,21 @@
 const fs = require('node:fs');
 
 class Thenable {
-  constructor() {
-    this.next = null;
-  }
+  next = null;
 
   then(fn) {
     this.fn = fn;
-    const next = new Thenable();
-    this.next = next;
-    return next;
+    this.next = new Thenable();
+    return this.next;
   }
 
   resolve(value) {
-    const fn = this.fn;
-    if (fn) {
-      const next = fn(value);
-      if (next) {
-        next.then((value) => {
-          this.next.resolve(value);
-        });
-      }
-    }
+    if (!this.fn) return;
+    const next = this.fn(value);
+    if (!next) return;
+    next.then((value) => {
+      this.next.resolve(value);
+    });
   }
 }
 

JavaScript/server.js

@@ -6,21 +6,21 @@ const routes = {
   '/': (request, callback) => {
     callback({
       apiVersion: '1.0',
-      resources: ['person', 'city']
+      resources: ['person', 'city'],
     });
   },
 
   '/person': (request, callback) => {
     callback({
       name: 'Alex',
-      age: 19
+      age: 19,
     });
   },
 
   '/city': (request, callback) => {
     callback({
       name: 'Kyiv',
-      country: 'Ukraine'
+      country: 'Ukraine',
     });
   }
 };
@@ -32,7 +32,6 @@ const server = http.createServer((req, res) => {
     res.end('Not found');
     return;
   }
-
   handler(req, (result) => {
     const json = JSON.stringify(result);
     res.writeHead(200, { 'Content-Type': 'application/json' });