Update "03-event-loop" folder

2-ui/99-ui-misc/03-event-loop/2-micro-macro-queue/solution.md

@@ -0,0 +1,50 @@
+The console output is: 1 7 3 5 2 6 4.
+
+The task is quite simple, we just need to know how microtask and macrotask queues work.
+
+Let's see what's going on, step by step.
+
+```js
+console.log(1);
+// The first line executes immediately, it outputs `1`.
+// Macrotask and microtask queues are empty, as of now.
+
+setTimeout(() => console.log(2));
+// `setTimeout` appends the callback to the macrotask queue.
+// - macrotask queue content:
+//   `console.log(2)`
+
+Promise.resolve().then(() => console.log(3));
+// The callback is appended to the microtask queue.
+// - microtask queue content:
+//   `console.log(3)`
+
+Promise.resolve().then(() => setTimeout(() => console.log(4)));
+// The callback with `setTimeout(...4)` is appended to microtasks
+// - microtask queue content:
+//   `console.log(3); setTimeout(...4)`
+
+Promise.resolve().then(() => console.log(5));
+// The callback is appended to the microtask queue
+// - microtask queue content:
+//   `console.log(3); setTimeout(...4); console.log(5)`
+
+setTimeout(() => console.log(6));
+// `setTimeout` appends the callback to macrotasks
+// - macrotask queue content:
+//   `console.log(2); console.log(6)`
+
+console.log(7);
+// Outputs 7 immediately.
+```
+
+To summarize,
+
+1. Numbers `1` и `7` show up immediately, because simple `console.log` calls don't use any queues.
+2. Then, after the main code flow is finished, the microtask queue runs.
+    - It has commands: `console.log(3); setTimeout(...4); console.log(5)`.
+    - Numbers `3` и `5` show up, while `setTimeout(() => console.log(4))` adds the `console.log(4)` call to the end of the macrotask queue.
+    - The macrotask queue is now: `console.log(2); console.log(6); console.log(4)`.
+3. After the microtask queue becomes empty, the macrotask queue executes. It outputs `2`, `6`, `4`.
+
+Finally, we have the output: `1 7 3 5 2 6 4`.

2-ui/99-ui-misc/03-event-loop/2-micro-macro-queue/task.md

@@ -0,0 +1,21 @@
+importance: 5
+
+---
+
+# What will be the output of this code?
+
+```js
+console.log(1);
+
+setTimeout(() => console.log(2));
+
+Promise.resolve().then(() => console.log(3));
+
+Promise.resolve().then(() => setTimeout(() => console.log(4)));
+
+Promise.resolve().then(() => console.log(5));
+
+setTimeout(() => console.log(6));
+
+console.log(7);
+```