Fri May 24 12:09:29 EEST 2024

readme.md

@@ -6,5 +6,7 @@
 
 # Chapters
 
+- [Chapter 02: Block scoped declarations](./src/02-block-scoped-declarations)
 - [Chapter 04: Classes](./src/04-classes)
-- [Chapter 05: New Object features](./src/05-new-object-features)
+- [Chapter 05: New `Object` features](./src/05-new-object-features)
+- [Chapter 11: New `Array` features](./src/11-new-array-features)

src/02-block-scoped-declarations/readme.md

@@ -0,0 +1,21 @@
+```js
+for (let i = 0; i < 5; i++) {
+  setTimeout(() => console.log(i), i * 1000);
+}
+```
+
+or
+
+```js
+for (var i = 0; i < 5; i++) {
+  setTimeout((capturedI) => console.log(capturedI), i * 1000, i);
+}
+```
+
+or
+
+```js
+for (var i = 0; i < 5; i++) {
+  ((capturedI) => setTimeout(() => console.log(capturedI), i * 1000))(i);
+}
+```

src/11-new-array-features/readme.md

@@ -1 +1,53 @@
-- https://www.freecodecamp.org/news/how-to-create-a-javascript-utility-library-like-lodash
+- https://www.freecodecamp.org/news/how-to-create-a-javascript-utility-library-like-lodash
+- [Convert from `Base64` to `byte array`](https://stackoverflow.com/questions/21797299/convert-base64-string-to-arraybuffer):
+
+```js
+function base64ToArrayBuffer(base64) {
+  // Solution 1
+  const binaryString = atob(base64);
+  const bytes = new Uint8Array(binaryString.length);
+
+  for (let i = 0; i < binaryString.length; i++) {
+    bytes[i] = binaryString.charCodeAt(i);
+  }
+
+  return bytes.buffer;
+}
+
+function base64ToArrayBuffer2(base64) {
+  // Solution 2
+  return Uint8Array.from(atob(base64), (c) => c.charCodeAt(0)).buffer;
+}
+
+// Benchmark function
+function benchmark(func, base64, iterations) {
+  const start = performance.now();
+
+  for (let i = 0; i < iterations; i++) {
+    func(base64);
+  }
+
+  const end = performance.now();
+
+  return end - start;
+}
+
+const base64Sample = "SGVsbG8gd29ybGQ="; // "Hello world" in base64
+const iterations = 100000;
+
+const time1 = benchmark(base64ToArrayBuffer, base64Sample, iterations);
+const time2 = benchmark(base64ToArrayBuffer2, base64Sample, iterations);
+
+console.log(`Solution 1 took: ${time1} ms`);
+console.log(`Solution 2 took: ${time2} ms`);
+
+if (time1 < time2) {
+  console.log("Solution 1 is faster.");
+} else if (time1 > time2) {
+  console.log("Solution 2 is faster.");
+} else {
+  console.log("Both solutions are roughly the same speed.");
+}
+
+// Solution 1 is faster
+```