Harshil Chovatiya - Day 7 and 8: Arrays, Functions - Advanced Concepts in JavaScript

Day 7: Arrays and Lists in JavaScript

Overview:

Arrays are used to store collections of data in JavaScript. They are versatile and can hold various data types, including numbers, strings, and objects.

In-Depth:

Creating Arrays:

You can create arrays using square brackets [] and populate them with values.

                        
                        
        var numbers = [1, 2, 3, 4, 5];
        var fruits = ["apple", "banana", "cherry"];
                        
                    

Accessing Array Elements:

Array elements are accessed by their index (starting at 0).

                        
                        
        var firstNumber = numbers[0]; // Access the first element
        var secondFruit = fruits[1]; // Access the second element
                        
                    

Modifying Arrays:

You can add, remove, and modify elements in an array.

                        
                        
        fruits.push("orange"); // Add an element to the end
        fruits.pop(); // Remove the last element
        fruits[1] = "grape"; // Modify an element
                        
                    

Array Length:

You can find the length of an array using the length property.

                        
                        
        var numCount = numbers.length; // Length of the 'numbers' array
                        
                    

Iterating Over Arrays:

Loops are often used to iterate over array elements.

                        
                        
        for (var i = 0; i < numbers.length; i++) {
          console.log(numbers[i]);
        }
                        
                    

Multidimensional Arrays:

Arrays can also hold other arrays, creating multidimensional structures.

                        
                        
        var matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
                        
                    

Day 8: Functions - Advanced Concepts in JavaScript

Overview:

Building upon the basics of functions, this day covers more advanced concepts and techniques.

In-Depth:

Function Scope:

Variables declared inside a function are typically scoped to that function and are not accessible outside of it.

                    
                    
    function greet() {
      var message = "Hello";
      console.log(message);
    }
    greet();
    console.log(message); // Error: 'message' is not defined
                    
                

Function Closures:

Functions can "close over" and retain access to their containing scope even after the outer function has finished executing.

                    
                    
    function makeCounter() {
      var count = 0;
      return function() {
        return ++count;
      };
    }
    var counter = makeCounter();
    console.log(counter()); // Output: 1
    console.log(counter()); // Output: 2
                    
                

Function Arguments:

Functions can accept a variable number of arguments using the `arguments` object or the rest parameter syntax.

                    
                    
    function calculateSum() {
      var sum = 0;
      for (var i = 0; i < arguments.length; i++) {
        sum += arguments[i];
      }
      return sum;
    }
    console.log(calculateSum(1, 2, 3)); // Output: 6
                    
                

Function Recursion:

A function can call itself, which is known as recursion.

                    
                    
    function factorial(n) {
      if (n === 0 || n === 1) {
        return 1;
      } else {
        return n * factorial(n - 1);
      }
    }
    console.log(factorial(5)); // Output: 120
                    
                

Function Hoisting:

Function declarations are hoisted to the top of their containing scope, allowing you to call a function before it's defined.

                    
                    
    sayHello(); // Works
    function sayHello() {
      console.log("Hello");
    }
                    
                

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