Init asynchonous programming example

Sample/asynchonous_programming/index.js

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+// Callbacks
+
+const task1 = (callAgain) => {
+  setTimeout(() => {
+    callAgain("Task 1");
+  }, 2000);
+};
+
+// Promise
+
+var promise = new Promise(
+  // Executor
+  function (resolve, reject) {
+    // Logic
+    // Successfull: resolve()
+    // Failure: reject()
+
+    task1((result) => {
+      resolve(result);
+    });
+  }
+);
+
+promise
+  .then(function (number) {
+    console.log("Then 1");
+    return number;
+  })
+  .then(function (data) {
+    return new Promise(function (resolve) {
+      console.log(`Then 2: ${data}`);
+      setTimeout(function () {
+        resolve(1000);
+      }, 5000);
+    });
+  })
+  .then(function (data) {
+    console.log(`Then 3: ${data}`);
+  })
+  .catch(function () {
+    console.log("Failure!");
+  })
+  .finally(function () {
+    console.log("Done!");
+  });
+
+// Async, await
+
+const getNewToDo = async () => {
+  let response = await fetch("https://jsonplaceholder.typicode.com/posts");
+  let data = await response.json();
+  return data;
+};
+
+getNewToDo().then((data) => {
+  console.log(">>> Data: ", data);
+});