Array Methods. What are they? How do they work? How do I use them? I will cover all of it in this post.
Before we start I would like to give you a brief summary of methods in JS
A method is a function which is a property of an object, which basically means it sits inside an object
In this example you can see there is a function inside the object
x. The function is just console logging
x object itself.
How to use a function inside an object?
You can use a method (we call function a method when it's inside an object) by adding a dot after the object variable. Like in the example below.
Now that you know how methods work let's dive into the main topic
What is an Array Method?
An array method can be used to do lots of cool things with an array. In this post, I am going to cover 3 Important array methods you will most probably use in your everyday coding sessions.
forEach() Array Method
So how the forEach array method basically works is that it calls a function once for each value in an array.
Here is our array :
So normally, if you want to loop over these array items you would use a for loop . But forEach makes things much easier for us.
Now let's say you want to know the index of all the items in the array mentioned above
You simply have to do this :
The forEach method takes in 3 parameters
( item, index, array )
Now let's say you want to capitalize a particular item in
You could do something like this :
Now let's move on to the next array method
map() Array Method
The map array method is similar to forEach but this method doesn't edit the original array instead it returns a new one. This means your original array is not mutated. Also unlike forEach, you need to have a return statement when you use
Here is an example of
As you can see it's really similar to ForEach but remember
map() doesn't change the original array so when you return a value you have to store it in a new variable. in this example
let = newArr.
Alright to the next one!
filter() Array Method
Like the name, array filter method creates a new array with all elements that pass the test implemented by the provided function.
Note: filter & map both are similar on how they work but filter just returns the elements which pass the evaluation
Here is an example of
As you can see all the numbers above 30 are filtered out to a new array. we are console logging the new filter variable which contains the new filtered array
That's all for this post I will try to cover more array methods in the future posts 😁 If you gained any knowledge from this post please leave like and do share it with your programming buddies 💜💛 Cya!
This is insightful, thanks for sharing!
A quick tip: You should add your code using code snippets rather than adding images. It's a better experience with syntax highlighting and great for SEO.
let filter = [10,10,20,30,50]; console.log(filter)
Append three backticks to achieve this like so:
I write daily web development tips that help you become a more efficient developer. 👨💻⚡️
Well written, always nice to see people using these methods.
Do keep in mind, depending on the array a native for loop can actually be the quicker/faster solutions. Especially filter and map can be pretty heavy according to some tests i've seen.