Most used JavaScript array functions

Most used JavaScript array functions

JavaScript is widely used and as well as one of the most important programming languages in the world. Learning it will help you make a strong foundation for web development. Most of the popular web development frameworks and libraries like Angular, Vue, React, Node and countless more are all written in JavaScript. To understand all these concepts, one has to master the basics of JavaScript like arrays, functions, loops, event handling, and other related topics. Here we will learn what arrays are and we will also list the most common JavaScript array functions used by programmers.

What are JavaScript Arrays?

An array is a data structure that stores values of a particular data type in an orderly collection. In JavaScript, the array consists of one or more elements, each having a numbered position allocated in the array. This position is known as the index of a particular element in the array.

Like most software languages, the index of arrays in JavaScript starts from 0. In JavaScript, one does not need to specify the size of the array as they are dynamic. This means the arrays do not have a fixed size and can shrink or grow according to the elements in them.

9 most used JavaScript Array functions

All the arrays in JavaScript have inbuilt functions which help us program easily. Here are some of the most commonly used functions in JavaScript array:

1. Push()

The push() function appends all the arguments in it to the end of the given array. Using this we can modify an existing array. When you call the push() method, it returns the total number of elements in the modified array after it has added the given arguments to the end of the array.

2. IndexOf()

The indexOf() function searches the array for the given element and then returns the index of the element’s first occurrence in the array. The first parameter is the value you want to search in the array and the second parameter is the starting index for the search.

If you do not pass a second parameter then the searching will begin from index 0, which is the default searching index. If the specified element does not exist in the array then the function will return -1.

3. ForEach()

The forEach() function has no return value and does not change nor return the original array. It is like a loop function that iterates over all the elements in the array. It is often used with other functions like filter(), map() and every(). All of these functions accept a callback function as the first parameter. The second parameter is optional, it is there to specify this value for the callback function.

4. Slice()

In JavaScript, you can create a sub-array using the slice() function. This function takes two parameters, the start, and the end argument. The elements between these two points are taken and the rest elements are not. The starting point is inclusive while the ending point is exclusive, meaning the starting point will be included in the sub-array but the ending point will not.

Note that the original array will be unchanged and the function will return a new array having the elements from the original array from the starting to the ending point but not the element indexed at the endpoint.

5. ToString()

The toString() function in JavaScript converts all of the elements of an array into strings. And it will return one big string with all of the elements of array separated by a commas.

6. Filter()

The filter() function helps us to filter a collection of elements based on the condition the programmer has provided. This callback is executed for each element in the array. If the callback function returns true then the element is added to a new array. Only the values which suffice the condition are added to the new array. The original array is left unchanged.

7. Concat()

The concat() function in JavaScript creates a new array having all the original elements of the given array plus the new elements specified by the user. It is used to join two arrays. The elements of the second array are added after the first array’s elements.

8. Shift()

The shift() function in JavaScript removes and returns us the first element of the given array. After using this function, all the elements in the array are shifted from one index to the left to fill the vacancy. If you attempt to use this function on an empty array, then it will return undefined. This function does not create a new array but modifies the given array. Once changed it can not be undone.

9. Unshift()

The unshift() functionality is the opposite of the shift() function. This function inserts the argument to the beginning of the given array. After using this, all the elements are shifted to the right by one position. This function also modifies the original array.


There are many more JavaScript array functions other than these mentioned above. If you ever feel lost and want help to understand where to start your coding journey then go check out Codedamn. There are amazing courses and blogs for web development and other coding concepts. Remember to practice coding on a daily basis. You can play around with your code on Codedamn’s online compiler as well.

Thank You for reading! If you have any suggestions or queries, do let us know in the comments.

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