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Asynchronous JavaScript: A Journey Through Callbacks, Promises, and Async/Await Introduction JavaScript is a powerful language that can do some pretty amazing things. One of the most important features of JavaScript is its ability to handle asynchronous operations. This means that JavaScript can do multiple things at the same time without waiting for one task to finish before starting another. This is a big deal because it allows for a smoother user experience. Today, we’re going to explore three key concepts in asynchronous JavaScript: callbacks, promises, and async/await. Callbacks A callback is a function that is passed as an argument to another function and is executed after some operation has been completed. Here’s a simple example: function greet ( name, callback ) { console . log ( 'Hello, ' + name); callback (); } greet ( 'John' , function ( ) { console . log ( 'The callback was invoked!' ); }); In this example, the greet function takes

  Understanding Lexical Scope and Closure in JavaScript Introduction JavaScript is a powerful programming language that has some unique concepts which can be a bit tricky to understand, especially for beginners. Two of these concepts are lexical scope and closure . Let’s break them down in a simple and easy-to-understand manner. What is Lexical Scope? In JavaScript, scope refers to the visibility or accessibility of variables, functions, and objects in some particular part of your code during runtime. In other words, it defines the portion of the code where a variable or a function can be accessed. Lexical scope , also known as static scope, is a type of scope in JavaScript. The word “lexical” refers to the fact that lexical scoping uses the location where the variable was declared within the source code to determine where that variable is available. Nested functions have access to variables declared in their outer scope. Let’s look at an example: function outerFunc ( ) { var o

Checking If a Key Exists in a JavaScript Map Hello there! Today, we’re going to learn about a very important concept in JavaScript: Maps. Specifically, we’ll learn how to check if a key exists in a Map. Don’t worry if you’re new to this, we’ll take it step by step. Let’s get started! What is a Map? In JavaScript, a Map is a built-in object that stores key-value pairs. In a Map, any value (both objects and primitive values) may be used as either a key or a value. This makes Maps very versatile! let myMap = new Map (); myMap. set ( 'name' , 'John' ); myMap. set ( 'age' , 15 ); In the above example, ‘name’ and ‘age’ are keys, while ‘John’ and 15 are their corresponding values. Checking if a Key Exists Now, let’s say we want to check if a certain key exists in our Map. How do we do that? JavaScript provides us with a very handy method called has() . let hasName = myMap. has ( 'name' ); // returns true let hasAddress = myMap. has ( 'address' ); /