02_advanced/uebungen/u13_dns-lookup/index.js

@@ -0,0 +1,54 @@
+// const dns = require('node:dns'); // commonjs
+import dns from 'node:dns'; // esm module
+import util from 'node:util';
+import color from 'chalk';
+
+const IP_V = 4; // we use IP protocol version 4
+const URL = 'google.de';
+
+const getIpBy = (url, ipVersion = 4) => {
+  return new Promise((resolve, reject) => {
+    // async process
+    dns.lookup(url, ipVersion, (error, address) => {
+      if (error) {
+        reject(error);
+      } else {
+        resolve({ address: address, family: ipVersion });
+      }
+    });
+  });
+};
+
+// Promises Unterobjekt von Node
+const getPromisesIpBy = (url, ipVersion = 4) => {
+  // async process
+  return dns.promises.lookup(url, ipVersion);
+};
+
+// Promisify Helferfunktion
+const getPromisifyIpBy = util.promisify(dns.lookup);
+
+// Test Cases:
+getIpBy(URL, IP_V)
+  .then((data) => {
+    console.log(data);
+  })
+  .catch((err) => {
+    console.log(color.red(err));
+  });
+
+getPromisesIpBy(URL)
+  .then((data) => {
+    console.log(data);
+  })
+  .catch((err) => {
+    console.log(color.red(err));
+  });
+
+getPromisifyIpBy(URL, IP_V)
+  .then((data) => {
+    console.log(data);
+  })
+  .catch((err) => {
+    console.log(color.red(err));
+  });