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Displaying loading animation on Fetch API calls

In web development, one of the most important part is to use REST api. When I start working on api with vanilla JS, I noticed small time difference between call and response. It's good practice to show end user something is happening after his interaction with website.
So here's the guide of showing loading animation on fetch api calls with vanilla JS.
Let's get started


Let's start with html.

<textarea> to get user input.
<button> to submit data.
<h1> to display response.

We are displaying loading animation using <div id="loading"></div>. This element is hidden by default. We are going to manipulate it, to show or hide it according our requirement.

Creating loader animation CSS

Stylesheet for loader

Working with Javascript

JS First part

In function displayLoading():

  • loader.className = "display"; this will add display class to
    <div id="#loading"></div>, which turn visibility: visible;

  • We are using setTimeout to hide loading animation after 5 second. Sometimes we may get late response, then timeout time should be increased.

Now, when displayLoading() called it will display loading animation and when hideLoading() called it will hide loading animation setting visibility: hidden;

Now for remaining JS
This part is straight forward. fetchHandler() to fetch data from api.

url I'm using is dummy url which only return 'Testing, you are' for any input.

JS second part

Here's the pen.

Hey there, I'm #codenewbie, started documenting my journey of learning. Any suggestions are welcome

Top comments (4)

mohamedmagdey profile image

It will be better to use

display: none

instead visibility because right now the element still exist.

shub78910 profile image
Shubham Hirakki

But then, the animation time will be irrespective of the actual loading time, that is, 5 seconds fixed. What if it takes longer or shorter time to load?

rahul1116 profile image
Rahul Ravindran

You're right. In that case all you need to do is store the timer id which is returned by the setTimeout in a global variable. Later if the response comes earlier than 5 secs, you just need to clear out the timer by adding one line in hideLoading()

clearTimeout( timerId ) // This will clear the timer and the .display class is anyway removed
Enter fullscreen mode Exit fullscreen mode

But in case of late response, you can get rid of the setTimeout logic altogether and it'll work fine

mukadas profile image
Mukadas Maltiti

I was overthinking this. Thought I needed to get a pending state status from the fetch api in order to display the load animation