My JavaScript Learning Journey:Understanding the JavaScript Event Loop and Concurrency Model

Today, I learned one of the most important concepts in JavaScript: the Event Loop and the Concurrency Model. JavaScript is Single-Threaded JavaScript is a single-threaded language. This means it can execute only one piece of JavaScript code at a time. For example: console.log("A"); console.log("B"); console.log("C"); Output: A B C JavaScript executes these statements one after another. What is the Call Stack? The Call Stack is where JavaScript executes functions. Whenever a function is called, it is added to the stack. After the function finishes executing, it is removed from the stack. Example: function one() { two(); } function two() { console.log("Hello"); } one(); Execution order: one() ↓ two() ↓ console.log() ↓ Stack becomes empty The Call Stack follows the Last In, First Out (LIFO) principle. What are Web APIs and Node APIs? Some operations take time, such as: Waiting for a timer Making an API request Reading a fi