JavaScript Methods

Methods

Methods are functions that are associated with a particular object. They are used to perform a specific task on the object. In JavaScript, methods are used to manipulate objects. They are written in the same way as functions, but they are defined within the object.

Methods are usually used to access and manipulate the data stored in an object. For example, you can use the length method to find out the length of a string. The push() method can be used to add a new element to an array.

In this tutorial, we will learn about different methods in JavaScript and how to use them.

String Methods

The String object has a number of methods that can be used to manipulate strings. The following are some of the most commonly used string methods:

• length() – Returns the length of a string.
• indexOf() – Returns the index of a specified character in a string.
• charAt() – Returns the character at a specified index in a string.
• substring() – Returns a substring of a specified string.
• toUpperCase() – Converts a string to uppercase.
• toLowerCase() – Converts a string to lowercase.
• trim() – Removes leading and trailing whitespace from a string.

Let's look at an example of how to use the length() method:

let str = 'Hello World';
let length = str.length;

console.log(length); // 11

In this example, we use the length() method to find the length of the string "Hello World". The result is 11, which is the number of characters in the string.

Array Methods

The Array object has a number of methods that can be used to manipulate arrays. The following are some of the most commonly used array methods:

• push() – Adds an element to the end of an array.
• pop() – Removes the last element from an array.
• shift() – Removes the first element from an array.
• unshift() – Adds an element to the beginning of an array.
• sort() – Sorts the elements of an array in ascending order.
• reverse() – Reverses the order of the elements in an array.

Let's look at an example of how to use the push() method:

let arr = ['apple', 'banana', 'cherry'];
arr.push('orange');

console.log(arr); // ['apple', 'banana', 'cherry', 'orange']

In this example, we use the push() method to add the element "orange" to the end of the array. The result is an array with five elements.

Object Methods

The Object object has a number of methods that can be used to manipulate objects. The following are some of the most commonly used object methods:

• hasOwnProperty() – Returns a boolean value indicating whether an object has a specified property.
• keys() – Returns an array of the keys of an object.
• values() – Returns an array of the values of an object.
• entries() – Returns an array of the [key, value] pairs of an object.

Let's look at an example of how to use the hasOwnProperty() method:

let obj = {
  name: 'John',
  age: 30
};

let hasName = obj.hasOwnProperty('name');

console.log(hasName); // true

In this example, we use the hasOwnProperty() method to check if the object has a property called "name". The result is true, indicating that the object does indeed have a property called "name".

Conclusion

In this tutorial, we learned about different methods in JavaScript and how to use them. We looked at string methods, array methods, and object methods. We also saw examples of how to use each of these methods.