Quick Review of 5 Of The Most Powerful JavaScript Methods

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In this article, I am going to discuss 5 of the most powerful JavaScript methods.

Now, let's start discussing these methods one by one.

  1. Split:

This method is used to split a string into an array of substrings and it returns the new array. Splitting of a string is done by searching for a pattern where the pattern is provided as the first parameter in the method's call.

Let's take one example so that you can understand it clearly:

const string = "Javascript is a programming language."
const newArr = string.split(" ");

If you noticed in the above code, I add space inside the .split method.

This space is used as a separator to split a string into an array of substrings. A split method doesn't change the value of the original string.

If you do console.log(newArr). You'll get a new array that looks like this.

["Javascript", "is", "a", "programming", "language."]

Now, your string is converted into an array. This method is one of the most powerful method.

2. Math.random:

This method returns a random number between 0 (inclusive) and 1 (exclusive).

It basically returns a random floating-point number(decimal number).

const randomNum = Math.random();

If you run the above code, you see a number between 0 and 1 like 0.4795164735135027.

If you want an integer instead of a floating-point number, you should wrap Math.random() with Math.floor(). Math.floor() method round a number downward to its nearest integer like so.

const randomNum = Math.floor(Math.random());

Now, if you want an integer between 0 and 20. Your code should look like this.

const number = 20;
const randomNum = Math.floor(Math.random()*number);

I hope you'll understand how Math.random() method works. Now, let's move to our third method.

3. forEach:

This method is used to loop through an array. If you used for loop to loop through an array, after reading this, you'll never go to use that.

let say we have an array:

const numbers = [1,2,3,4,5];

Now, if you want to multiply each number inside an array by 2, How do you do that?

Here, the forEach() method comes into play. Let see how it works.

Basically, the forEach() method calls a function once for each element in an array, in order.

const numbers = [1,2,3,4,5];
numbers.forEach(number => {


So, in the above code for each number in an array, we call a function which multiplies each number by 2. I think, now you understand how to use forEach method.

4. filter():

The filter() method creates a new array with all elements that pass the test implemented by the provided function.

Now, let's take one example to clearly understand it.

const ages = [18,15,10,20,22];
const filterArr = ages.filter(age => age>18);

So, in the above example, I take an array of ages and apply the filter method to it.

Filter method executes a function for each element in an array and checks whether it is satisfying the condition provided by the given function or not. If it satisfies the given condition, it returns that element to the new array otherwise it doesn't store that element in the filterArr array.

I hope now you have a clear understanding of how to use the filter method. This method is basically used to implement delete functionality in various apps

Note: filter() method does not change the value of the original array.

filter() method does not run the function for array elements without values.

5. Map method:-

This method calls a provided function for each element in an array and then it creates a new array with the results of calling a function for every array element.

Now, let's take an example to understand it better.

const numbers = [1,2,3,4,5];
const newArr = numbers.map(number => {
    return number*number;

In the above code, I take a numbers array and then apply the .map method to it. For each number, I call a function that returns a square of that number and creates a new array named newArr

Now, if you do console.log(newArr). You will get a new array that contains a square of numbers like this.

[1, 4, 9, 16, 25]

This method doesn't change the value of the original array.


Now, We have covered 5 of the most powerful javascript methods. These methods are very useful and help us to write cleaner code.

Thanks for reading this blog

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Dmitry's photo

Seriously? You presumed we don't know these functions?

Bakshi's photo

now i know that these people exists:d

Nikola Ivanov's photo

The more appropriate name would be: "5 JS methods you probably don't know if you heard about JS yesterday".

Adarsh Hegde's photo

These are elementary. 🤷‍♂️

Benoit Schiex's photo

Maybe you should wait to gain a bit more of expertise with JS before writing articles about it and sounds relevant.