new class js -advanced

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/dns_lookup/solution_1.js

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+const dns = require('dns');
+
+const IP_V = 4; // we use IP protocol version 4
+const URL = 'de.webmasters-europe.org';
+
+// Solution 1: Detailed variant with Promise object
+const getIp = (url, ip) => {
+  return new Promise((resolve, reject) => {
+    dns.lookup(url, ip, (error, data) => {
+      if (error) {
+        reject(error);
+      } else {
+        resolve({ address: data, family: ip });
+      }
+    });
+  });
+};
+
+getIp(URL, IP_V)
+  .then((data) => console.log(`IP adress = ${data.address}`))
+  .catch((err) => console.error(err));
+
+// dns.lookup(URL, IP_V, (error, address) => {
+//   if (error) {
+//     console.log('error: could not lookup host');
+//   } else {
+//     console.log('IP address = ' + address);
+//   }
+// });

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/dns_lookup/solution_2.js

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+const dns = require('dns');
+
+const IP_V = 4; // we use IP protocol version 4
+const URL = 'de.webmasters-europe.org';
+
+// Solution 2: Variant with promises subobject
+const getIpPromises = (url, ip) => {
+  return dns.promises.lookup(url, ip);
+};
+
+getIpPromises(URL, IP_V)
+  .then((data) => console.log(`IP adress = ${data.address}`))
+  .catch((err) => console.error(err));
+
+// dns.lookup(URL, IP_V, (error, address) => {
+//   if (error) {
+//     console.log('error: could not lookup host');
+//   } else {
+//     console.log('IP address = ' + address);
+//   }
+// });

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/dns_lookup/solution_3.js

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+const dns = require('dns');
+const util = require('util');
+
+const IP_V = 4; // we use IP protocol version 4
+const URL = 'de.webmasters-europe.org';
+
+// Solution 3: Variant with util module
+const getIpPromisify = util.promisify(dns.lookup);
+
+getIpPromisify(URL, IP_V)
+  .then((data) => console.log(`IP adress = ${data.address}`))
+  .catch((err) => console.error(err));
+
+// dns.lookup(URL, IP_V, (error, address) => {
+//   if (error) {
+//     console.log('error: could not lookup host');
+//   } else {
+//     console.log('IP address = ' + address);
+//   }
+// });

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/getFileContent/data/file_1.txt

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+This is the contents of file 01.

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/getFileContent/data/file_2.txt

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+This is the contents of file 02.

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/getFileContent/data/file_3.txt

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+This is the contents of file 03.

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/getFileContent/data/file_4.txt

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+This is the contents of file 04.

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/getFileContent/data/file_5.txt

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+This is the contents of file 05.

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/getFileContent/data/file_6.txt

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+This is the contents of file 06.

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/getFileContent/index.js

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+const fs = require('fs');
+
+const getFileContent = (name, encoding = 'UTF8') => {
+  return new Promise((resolve, reject) => {
+    fs.readFile(name, encoding, (error, content) => {
+      if (error) {
+        reject(`could not read file ${name}`);
+      } else {
+        resolve(content);
+      }
+    });
+  });
+};
+
+Promise.all([
+  getFileContent('data/file_1.txt'),
+  getFileContent('data/file_2.txt'),
+  getFileContent('data/file_3.txt'),
+  getFileContent('data/file_4.txt'),
+  getFileContent('data/file_5.txt'),
+  getFileContent('data/file_6.txt'),
+])
+  .then((contents) =>
+    contents.forEach((content) => {
+      console.log(content);
+    })
+  )
+  .catch((error) => {
+    console.log(error);
+  });

02_advanced/MATERIAL/advanced-js/lesson_03/solutions/printWords/index.js

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+// print a phrase, a word at a time:
+// workaround to avoid the pyramid of doom
+
+const words = 'The pyramid of doom keeps growing.';
+
+const printWords = (str = '', idx = 0) => {
+  const words = str.split(/\s/);
+  // Guard
+  if (idx >= words.length) return '';
+
+  console.log(words[idx]);
+
+  setTimeout(() => {
+    printWords(str, ++idx);
+  }, 1000);
+};
+
+printWords(words);