JS Basics - Class IV

Lecture 41 :- JS Basics - Class IV

In "JS Basics - Class IV," we'll explore some additional important topics in JavaScript, including working with arrays and objects, using built-in array methods, and handling errors with try...catch blocks. Let's dive in:

Array Methods: JavaScript provides various built-in array methods to manipulate arrays efficiently.

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let numbers = [1, 2, 3, 4, 5]; // Push and Pop numbers.push(6); // Add an element to the end of the array numbers.pop(); // Remove the last element from the array // Shift and Unshift numbers.unshift(0); // Add an element to the beginning of the array numbers.shift(); // Remove the first element from the array // Slice let slicedArray = numbers.slice(2, 4); // Extract elements from index 2 to index 3 (end index is exclusive) // Splice numbers.splice(1, 2); // Remove two elements starting from index 1 numbers.splice(1, 0, 9, 10); // Insert elements (9 and 10) at index 1 without removing any element

Object Methods: Objects in JavaScript have some useful built-in methods.

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let person = {  name: "Alice",  age: 25, }; // Object.keys let keys = Object.keys(person); // Returns an array of object keys: ["name", "age"] // Object.values let values = Object.values(person); // Returns an array of object values: ["Alice", 25] // Object.entries let entries = Object.entries(person); // Returns an array of key-value pairs: [["name", "Alice"], ["age", 25]]

Iterating Arrays and Objects: You can use different approaches to iterate through arrays and objects.

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// For loop for arrays for (let i = 0; i < numbers.length; i++) {  console.log(numbers[i]); } // For...of loop for arrays for (let num of numbers) {  console.log(num); } // For...in loop for objects for (let key in person) {  console.log(key + ": " + person[key]); }

Error Handling with try...catch: You can use try...catch blocks to handle errors gracefully and prevent the program from crashing.

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try {  // Code that might throw an error  let result = calculateSomething();  console.log("Result: " + result); } catch (error) {  // Code to handle the error  console.error("An error occurred: " + error.message); }

JSON (JavaScript Object Notation): JSON is a format used to exchange data between servers and web applications. JavaScript provides methods to work with JSON.

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// Convert JavaScript object to JSON string let person = { name: "Alice", age: 25 }; let jsonStr = JSON.stringify(person); // Convert JSON string to JavaScript object let jsonStr = '{"name": "Alice", "age": 25}'; let person = JSON.parse(jsonStr);

These concepts are essential for working effectively with arrays, objects, and handling errors in JavaScript applications. As you become more proficient in JavaScript, you'll be able to build more sophisticated and efficient programs.

Remember to practice regularly and experiment with different scenarios to reinforce your understanding. If you have any specific questions or need further clarification on any topic, feel free to ask! Happy coding!