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JavaScript Array Methods

In JavaScript, arrays have a number of built-in methods that allow you to manipulate and operate on the elements of an array. These methods can be used to add, remove, and modify array elements, as well as to perform common operations such as sorting and filtering.

Common Array Methods

Here are some of the most commonly used array methods in JavaScript:

push

Add one or more elements to the end of an array. It returns the new length of the array.

var numbers = [1, 2, 3];
numbers.push(4, 5);
console.log(numbers); // Output: [1, 2, 3, 4, 5]

pop

Remove the last element of an array. It returns the removed element.

var numbers = [1, 2, 3, 4, 5];
numbers.pop();
console.log(numbers); // Output: [1, 2, 3, 4]

shift

Remove the first element of an array. It returns the removed element.

var numbers = [1, 2, 3, 4, 5];
numbers.shift();
console.log(numbers); // Output: [2, 3, 4, 5]

unshift

Add one or more elements to the beginning of an array. It returns the new length of the array.

var numbers = [1, 2, 3];
numbers.unshift(0);
console.log(numbers); // Output: [0, 1, 2, 3]

sort()

Sort the elements of an array in ascending or descending order. It returns the sorted array.

var numbers = [4, 1, 3, 5, 2];
numbers.sort();
console.log(numbers); // Output: [1, 2, 3, 4, 5]

You can also provide a custom sorting function to the sort method, which allows you to control the way the elements are sorted. For example, to sort the array in descending order, you can use the following code:

var numbers = [4, 1, 3, 5, 2];
numbers.sort(function(a, b) {
  return b - a;
});
console.log(numbers); // Output: [5, 4, 3, 2, 1]

filter

Create a new array with only the elements that satisfy a certain condition. It takes a callback function as an argument, which is called for each element of the array, and returns true if the element should be included in the new array, or false if it should be excluded.

var numbers = [1, 2, 3, 4, 5];
var evenNumbers = numbers.filter(function(num) {
  return num % 2 == 0;
});
console.log(evenNumbers); // Output: [2, 4]

List of JavaScript array methods

MethodDescription
concat()Joins two or more arrays and returns a new array
every()Determines whether all elements in an array pass a test
filter()Creates a new array with all elements that pass a test
find()Returns the first element in an array that passes a test
forEach()Calls a function for each element in an array
map()Creates a new array with the results of calling a function for each element
pop()Removes the last element from an array and returns that element
push()Adds one or more elements to the end of an array and returns the new length
reduce()Reduces an array to a single value by applying a function to each element
shift()Removes the first element from an array and returns that element
unshift()Adds one or more elements to the beginning of an array and returns the new length
slice()Extracts a section of an array and returns a new array
sort()Sorts the elements of an array
splice()Adds or removes elements from an array
toString()Converts an array to a string and returns the result
indexOf()Returns the index of the first occurrence of a value in an array
lastIndexOf()Returns the index of the last occurrence of a value in an array
join()Joins all elements of an array into a string and returns the result
reverse()Reverses the order of the elements in an array