JavaScript Array methods

Hello! In this article, I'm going to give a short description and quick examples of some array methods in JS.

Overview
Arrays are used to store multiple values in a single variable. This is compared to a variable that can store only one value. Each item in an array has a number attached to it, called a numeric index, that allows you to access it. In JavaScript, arrays start at index zero and can be manipulated with various methods.

at()

• The method takes an integer value and returns an item at that index, allowing for positive an negative integers.

Example
[2, 3, 4, 5].at(1) //--> 3

push()

• The method adds one or more to the end of an array and it returns the new length of an array.

Example:
[2, 3, 4, 5].push(6) //--> [2, 3, 4, 5, 6]

pop()

• It removes the last element of an array and returns that element. The method changes the length of an array.

Example:
[2, 3, 4, 5].pop() //--> [2, 3, 4]

fill()

• Changes all elements in an array to a static value from a start index (0) to an end index (arr.length). Returns the modified array.

Example:
[2, 3, 4, 5].fill(1) //--> [1, 1, 1]

join()

• Creates and returns a new string by concatenating all of the elements in an array, seperated by a comma or any specified seperator string.

Example:
[2, 3, 4, 5].join('') //--> '2345' (string)

shift()

• Removes the first element of an array and returns that removed element.

Example:
[2, 3, 4, 5].shift() //--> [3, 4, 5]


reverse()

• Elements in an array will be turned towards the direction opposite to that previously stated.

Example:
[2, 3, 4, 5].reverse() //--> [5, 4, 3, 2]


unshift()

• Adds one or more elements to the beginning of an array.

Example:
[2, 3, 4, 5].unshift(1) //--> [1, 2, 3, 4, 5]


includes()

• Determines whether an array includes a certain value among its entries, returning true or false.

Example:
[2, 3, 4, 5].includes(4) //--> true


map()

• Creates a new array by calling a function for every array element.

Example:
[2, 3, 4, 5].map(item => 2 * item) //--> [4, 6, 8, 10]


filter()

• Creates a shallow copy of a portion of a given array, filtered down to just the elements from the given array that pass the test implemented by the provided function.

Example:
[2, 3, 4, 5].filter(item => item > 3) //--> [4, 5]


find()

• Used to get the value of the first element in an array that satisfies the provided condition.

Example:
[2, 3, 4, 5].find(item => item > 3) //--> 4 (first match)


every()

• Tests whether all elements in an array pass the test implemented by the provided function and returns a boolean.

Example:
[2, 3, 4, 5].every(item => item > 0) //--> true


findIndex()

• Returns the index of the first element in an array that satisfies the provided testing function. If no elements satisfy the testing function, -1 is returned.

Example:
[2, 3, 4, 5].findIndex(item => item === 3) //--> 1


That's it!! #HappyCoding

PS: Watch out for Episode 2 of Array methods soon!

Cheers.