Add forst two tasks

tshemsedinov · tshemsedinov · commit 0e74b335c250 · 2024-07-18T00:28:54.000+03:00
diff --git a/JavaScript/Tasks/1-promisify.js b/JavaScript/Tasks/1-promisify.js
@@ -0,0 +1,28 @@
+'use strict';
+
+// Task: implement cancel using AbortController,
+// AbortSignal, or passing `timeout` as an option
+
+const promisify = (fn) => (...args) => {
+  const promise = new Promise((resolve, reject) => {
+    const callback = (err, data) => {
+      if (err) reject(err);
+      else resolve(data);
+    };
+    fn(...args, callback);
+  });
+  return promise;
+};
+
+// Usage
+
+const fs = require('node:fs');
+const read = promisify(fs.readFile);
+
+const main = async () => {
+  const fileName = '1-promisify.js';
+  const data = await read(fileName, 'utf8');
+  console.log(`File "${fileName}" size: ${data.length}`);
+};
+
+main();
diff --git a/JavaScript/Tasks/2-multi-iterate.js b/JavaScript/Tasks/2-multi-iterate.js
@@ -0,0 +1,64 @@
+'use strict';
+
+// Task: implement ability to use Timer in multiple places
+// In usage section we have 3 sections with async iterators
+// generated from single timer, just last sections iterates
+// as of now. Fix this to allow all sections to iterate
+
+class Timer {
+  #counter = 0;
+  #resolve = null;
+
+  constructor(delay) {
+    setInterval(() => {
+      this.#counter++;
+      if (this.#resolve) {
+        this.#resolve({
+          value: this.#counter,
+          done: false,
+        });
+      }
+    }, delay);
+  }
+
+  [Symbol.asyncIterator]() {
+    const next = () => new Promise((resolve) => {
+      this.#resolve = resolve;
+    });
+    const iterator = { next };
+    return iterator;
+  }
+}
+
+// Usage
+
+const main = async () => {
+  const timer = new Timer(1000);
+
+  (async () => {
+    console.log('Section 1 start');
+    for await (const step of timer) {
+      console.log({ section: 1, step });
+    }
+  })();
+
+  (async () => {
+    console.log('Section 2 start');
+    const iter = timer[Symbol.asyncIterator]();
+    do {
+      const { value, done } = await iter.next();
+      console.log({ section: 2, step: value, done });
+    } while (true);
+  })();
+
+  (async () => {
+    console.log('Section 3 start');
+    const iter = timer[Symbol.asyncIterator]();
+    do {
+      const { value, done } = await iter.next();
+      console.log({ section: 3, step: value, done });
+    } while (true);
+  })();
+};
+
+main();
