\/\/ This is a single-line comment\/* This is a multi-line comment *\/<\/code><\/pre> <\/div> <\/div>\n
Printing Output<\/h3>\n\n- Definition<\/strong>: console.log() is used to print output to the console.<\/li>\n
- Explanation<\/strong>: Useful for debugging or checking variable values.<\/li>\n<\/ul>\n
console.log("Hello, World!"); \/\/ Outputs: Hello, World!<\/code><\/pre> <\/div> <\/div>\n
Variables<\/h3>\n\n- Definition<\/strong>: Variables store data like numbers, text, or objects.<\/li>\n
- Explanation<\/strong>: Declare variables with let, const, or Var<\/li>\n<\/ul>\n
let x = 5; \/\/ Can be reassignedconst y = 10; \/\/ Cannot be reassignedvar z = 15; \/\/ Legacy variable declaration (avoid in modern JavaScript)<\/code><\/pre> <\/div> <\/div>\n
2. Data Types and Casting<\/h2>\nCommon Data Types<\/h3>\n\n- Definition<\/strong>: Data types specify the kind of value a variable holds.<\/li>\n
- Explanation<\/strong>: JavaScript variables can hold numbers, strings, boolean, objects, etc.<\/li>\n<\/ul>\n
let age = 25; \/\/ Numberlet name = "Kaashiv"; \/\/ Stringlet isActive = true; \/\/ Booleanlet person = {name: "Bob"}; \/\/ Objectlet colors = ["red", "blue"]; \/\/ Array<\/code><\/pre> <\/div> <\/div>\n
Type Conversion<\/h3>\n\n- Definition<\/strong>: Type conversion changes the data type of a value.<\/li>\n
- Explanation<\/strong>: Use String(), Number(), Boolean() to convert values.<\/li>\n<\/ul>\n
let x = String(123); \/\/ Converts 123 to "123"let y = Number("5"); \/\/ Converts "5" to 5<\/code><\/pre> <\/div> <\/div>\n
3. Basic Operators<\/h2>\n\n- Definition<\/strong>: Operators perform operations on variables and values.<\/li>\n
- Explanation<\/strong>: JavaScript has arithmetic, comparison, and logical operators.<\/li>\n<\/ul>\n
let sum = a + b; \/\/ Additionlet isEqual = a == b; \/\/ Comparisonlet result = a && b; \/\/ Logical AND<\/code><\/pre> <\/div> <\/div>\n
4. Strings<\/h2>\n\n- Definition<\/strong>: Strings are sequences of characters for storing text.<\/li>\n
- Explanation<\/strong>: JavaScript strings have various methods for manipulation, like changing case, finding length, etc.<\/li>\n<\/ul>\n
let greeting = "Hello, World!";console.log(greeting.toUpperCase()); \/\/ Outputs: HELLO, WORLD!<\/code><\/pre> <\/div> <\/div>\n
String Concatenation<\/h3>\n\n- Explanation<\/strong>: Use +\u00a0 or template literals with ${} for concatenating strings.<\/li>\n<\/ul>\n
let firstName = "Alice";console.log(`Hello, ${firstName}!`); \/\/ Outputs: Hello, Alice!<\/code><\/pre> <\/div> <\/div>\n
5. Arrays<\/h2>\n\n- Definition<\/strong>: Arrays store multiple values in a single variable.<\/li>\n
- Explanation<\/strong>: JavaScript arrays are dynamic and can hold any type of data.<\/li>\n<\/ul>\n
let fruits = ["apple", "banana", "cherry"];console.log(fruits[0]); \/\/ Outputs: apple<\/code><\/pre> <\/div> <\/div>\n
Array Methods<\/h3>\n\n- Explanation<\/strong>: Arrays have built-in methods like push(), pop(), shift(), and map().<\/li>\n<\/ul>\n
fruits.push("orange"); \/\/ Adds "orange" to the endlet upperFruits = fruits.map(fruit => fruit.toUpperCase());<\/code><\/pre> <\/div> <\/div>\n
6. Objects<\/h2>\n\n- Definition<\/strong>: Objects are collections of key-value pairs.<\/li>\n
- Explanation<\/strong>: Useful for storing related data or complex structures.<\/li>\n<\/ul>\n
let person = { name: "Alice", age: 25, greet: function() { console.log("Hello, " + this.name); }};console.log(person.name); \/\/ Outputs: Alice<\/code><\/pre> <\/div> <\/div>\n
7. Conditional Statements<\/h2>\nIf-Else<\/h3>\n\n- Definition<\/strong>: Conditional statements control program flow based on conditions.<\/li>\n
- Explanation<\/strong>: Use if, else if, and else to make decisions in code.<\/li>\n<\/ul>\n
let age = 18;if (age >= 18) { console.log("Adult");} else { console.log("Minor");}<\/code><\/pre> <\/div> <\/div>\n
Ternary Operator<\/h2>\n
Explanation<\/strong>: A shorthand for if-else that uses condition ?<\/strong> expression-If-True : expression-If-False.<\/p>\n let status = age >= 18 ? "Adult" : "Minor";<\/code><\/pre> <\/div> <\/div>\n
8. Loops<\/h2>\nFor Loop<\/h3>\n\n- Definition<\/strong>: for loops run a block of code a set number of times.<\/li>\n
- Explanation<\/strong>: Useful for iterating over arrays or repeating actions.<\/li>\n<\/ul>\n
for (let i = 0; i < 5; i++) { console.log(i);}<\/code><\/pre> <\/div> <\/div>\n
While Loop<\/h3>\n\n- Definition<\/strong>: while loops run as long as a condition is true.<\/li>\n
- Explanation<\/strong>: Useful when the number of iterations isn\u2019t predetermined.<\/li>\n<\/ul>\n
let count = 0;while (count < 5) { console.log(count); count++;}<\/code><\/pre> <\/div> <\/div>\n
9. Functions<\/h2>\nFunction Declaration<\/h3>\n\n- Definition<\/strong>: Functions are reusable blocks of code that perform specific tasks.<\/li>\n
- Explanation<\/strong>: Define functions with function keyword or as arrow functions.<\/li>\n<\/ul>\n
function greet(name) { return `Hello, ${name}!`;}console.log(greet("Alice")); \/\/ Outputs: Hello, Alice!<\/code><\/pre> <\/div> <\/div>\n
Arrow Functions<\/h3>\n\n- Explanation<\/strong>: A shorter syntax for functions introduced in ES6.<\/li>\n<\/ul>\n
const add = (a, b) => a + b;console.log(add(5, 3)); \/\/ Outputs: 8<\/code><\/pre> <\/div> <\/div>\n
10. Exception Handling<\/h2>\n\n- Definition<\/strong>: Exception handling catches and manages errors in code.<\/li>\n
- Explanation<\/strong>: Use try,catch,finally, to handle exceptions gracefully.<\/li>\n<\/ul>\n
try { let result = 10 \/ 0;} catch (error) { console.log("An error occurred: " + error.message);} finally { console.log("This runs regardless of error.");}<\/code><\/pre> <\/div> <\/div>\n
11. Object-Oriented Programming (OOP)<\/h2>\nClasses<\/h3>\n\n- Definition<\/strong>: Classes are blueprints for creating objects.<\/li>\n
- Explanation<\/strong>: Use Class keyword to define classes and instantiate objects.<\/li>\n<\/ul>\n
class Car { constructor(brand) { this.brand = brand; } drive() { console.log(`${this.brand} is driving`); }}let myCar = new Car("Toyota");myCar.drive(); \/\/ Outputs: Toyota is driving<\/code><\/pre> <\/div> <\/div>\n
Inheritance<\/h3>\n\n- Definition<\/strong>: Inheritance allows one class to inherit properties and methods from another.<\/li>\n
- Explanation<\/strong>: Use extends to create subclasses.<\/li>\n<\/ul>\n
class ElectricCar extends Car { charge() { console.log(`${this.brand} is charging`); }}let myTesla = new ElectricCar("Tesla");myTesla.charge(); \/\/ Outputs: Tesla is charging<\/code><\/pre> <\/div> <\/div>\n
12. Promises (Asynchronous JavaScript)<\/h2>\n\n- Definition<\/strong>: Promises handle asynchronous operations, like loading data from a server.<\/li>\n
- Explanation<\/strong>: A promise can be resolved (successful) or rejected (error).<\/li>\n<\/ul>\n
let myPromise = new Promise((resolve, reject) => { let success = true; if (success) { resolve("Promise resolved!"); } else { reject("Promise rejected."); }});myPromise .then(response => console.log(response)) .catch(error => console.log(error));<\/code><\/pre> <\/div> <\/div>\n
13. Document Object Model (DOM) Manipulation<\/h2>\n\n- Definition<\/strong>: The DOM represents the structure of a webpage.<\/li>\n
- Explanation<\/strong>: JavaScript can manipulate HTML elements through the DOM.<\/li>\n<\/ul>\n
document.getElementById("myElement").innerHTML = "Hello, World!";<\/code><\/pre> <\/div> <\/div>\n
Event Listeners<\/h3>\n\n- Explanation<\/strong>: addEventListener() allows you to execute code in response to user actions like clicks.<\/li>\n<\/ul>\n
document.getElementById("myButton").addEventListener("click", function() { alert("Button clicked!");});<\/code><\/pre> <\/div> <\/div>\n
<\/p>\n","protected":false},"excerpt":{"rendered":"A JavaScript cheat sheet for freshers offers a concise reference to key JavaScript syntax, functions, and concepts, helping…","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"csco_singular_sidebar":"","csco_page_header_type":"","csco_page_load_nextpost":"","footnotes":""},"categories":[3383,3203],"tags":[],"class_list":["post-3975","post","type-post","status-publish","format-standard","category-java-script","category-programming","cs-entry"],"_links":{"self":[{"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/posts\/3975","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/comments?post=3975"}],"version-history":[{"count":2,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/posts\/3975\/revisions"}],"predecessor-version":[{"id":3977,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/posts\/3975\/revisions\/3977"}],"wp:attachment":[{"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/media?parent=3975"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/categories?post=3975"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/tags?post=3975"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}