String Methods

1. toUpperCase() and toLowerCase()

These methods allow you to convert a string to uppercase or lowercase, respectively.

const text = "Hello, World!";
const upperCaseText = text.toUpperCase(); // "HELLO, WORLD!"
const lowerCaseText = text.toLowerCase(); // "hello, world!"

2. trim()

trim() removes whitespace from both ends of a string.

const text = "   Hello, World!   ";
const trimmedText = text.trim(); // "Hello, World!"

3. split()

split() divides a string into an array of substrings based on a specified delimiter.

const text = "apple,banana,cherry";
const fruits = text.split(","); // ["apple", "banana", "cherry"]

Array Methods

1. push() and pop()

push() adds elements to the end of an array, while pop() removes and returns the last element.

const fruits = ["apple", "banana"];
fruits.push("cherry"); // ["apple", "banana", "cherry"]
const removedFruit = fruits.pop(); // "cherry"

2. forEach()

forEach() executes a provided function once for each array element.

const numbers = [1, 2, 3];
numbers.forEach((number) => {
  console.log(number); // 1, 2, 3
});

3. map()

map() creates a new array by applying a function to each element of an existing array.

const numbers = [1, 2, 3];
const doubledNumbers = numbers.map((number) => number \* 2); // [2, 4, 6]

Object Methods

1. hasOwnProperty()

hasOwnProperty() checks if an object has a specific property.

const person = { name: "John", age: 30 };
const hasName = person.hasOwnProperty("name"); // true
const hasAddress = person.hasOwnProperty("address"); // false

2. keys()

keys() returns an array of an object's property names.

const person = { name: "John", age: 30 };
const properties = Object.keys(person); // ["name", "age"]

3. values()

values() returns an array of an object's property values.

const person = { name: "John", age: 30 };
const values = Object.values(person); // ["John", 30]

Conclusion

These are just a few of the many methods available in JavaScript. By mastering these common methods, you'll be well-equipped to work with strings, arrays, and objects effectively in your JavaScript projects. Take the time to practice and explore these methods further to become a more proficient JavaScript developer.