How to Create a Rotating Glow Effect on Buttons with CSS and JavaScript

Ever wondered how websites create those eye-catching buttons with glowing, rotating effects? These effects can captivate users and elevate your website's UI/UX. Let’s explore how to build them step-by-step with CSS and a bit of JavaScript.

Step 1: Create the Button Layout

Let’s make a simple button at first-

<button>WHY CHOOSE US</button>

button {
  width: 250px;
  height: 80px;
  border-radius: 3rem;
  outline: none;
  background: black;
  border: 2px solid transparent;
  color: white;
  cursor: pointer;
}

/* ... Other styles ... */

It will look like this-

Step 2: Adding a Gradient Effect

Now, let’s talk about a special kind of gradient called a conic gradient. Have you heard of it? While linear gradients smoothly transition colors along a straight line and radial gradients blend colors outward from the center of a circle, conic gradients transition colors around a central point, forming a circular or cone-like pattern. It's a unique way to create dynamic and visually interesting designs.

See the difference below-

We will use the conic gradient for this effect. Let’s add that to our button-

  background: conic-gradient(from 0, transparent, white 10%, transparent 20%)
    border-box;

The CSS snippet involves a conic gradient and uses border-box for background sizing. Here's a breakdown of what's happening:

Conic Gradient Breakdown

conic-gradient(from 0, transparent, white 10%, transparent 20%):

• • from 0: The gradient starts at an angle of 0 degrees (the top of the circle) and proceeds clockwise.

    • transparent: The gradient begins with a fully transparent color.

    • white 10%: At 10% of the total gradient's circumference, the color transitions to white.

    • transparent 20%: At 20% of the gradient's circumference, it transitions back to transparent.

    • This pattern creates a "slice" of white surrounded by transparency.

border-box

• border-box: The gradient applies to the area that includes the content, padding, and border of the element. This means the gradient will cover the entire element's box, up to the outer edge of the border.

After applying this effect, the button will look like this-

Now, we will use this conic gradient as our gradient border of the button. How can we do that?

We will use the power of box-sizing here. We will make multiple backgrounds for this button. The top background of the button will be a solid background which will have padding-box as box-sizing which means that it won’t stretch till the border. See the code below-

  background: linear-gradient(black, black) padding-box,
    conic-gradient(from 0, transparent, white 10%, transparent 20%) border-box;

So, now we have a black background that covers the button, including its content and padding. The conic-gradient we added earlier stretches all the way to the border. Since the border is transparent, we can see the conic gradient's 2px thickness showing through the border. Now, the button looks like this-

Step 3: Animating the Gradient

We’ve added that shiny glow effect to our button! Now, let’s make it move. To do this, we’ll need a little JavaScript. But first, we’ll update the CSS to make it more flexible and dynamic.

  background: linear-gradient(black, black) padding-box,
    conic-gradient(
        from var(--angle, 0),
        transparent,
        white 10%,
        transparent 20%
      )
      border-box;

Here, the only difference from previous section is that, we have introduced a CSS variable called --angle. from var(--angle, 0) means that if the --angle value is not defined, the default value will be 0 which was same like before. And, now we will change this --angle value from 0 to 360 by Javascript. As a result, the conic-gradient will move from 0 to 360 degrees and make that glowing rotating effect. Let’s see the JavaScript part now-

document.addEventListener("DOMContentLoaded", () => {
  const element = document.querySelector(".rotating");
  let angle = 0;
  const rotate = () => {
    angle = (angle + 1) % 360; // Increment angle and keep it within 0-360
    element.style.setProperty("--angle", `${angle}deg`);
    requestAnimationFrame(rotate);
  };

  rotate();
});

Very simple operation. After the DOM contents are loaded, we are calling a function called rotate(). This function is incrementing the angle by 1 on each iteration and setting that value to the button’s CSS variable --angle. That eventually changes the place of the conic-gradient. We are calling this function iteratively using a built in function called requestAnimationFrame. This is a special Javascript function like setInterval or setTimeOut. Let’s get into a bit detail of this requestAnimationFrame function-

What It Does:

1. Keeps animations smooth: It synchronizes your animations with the screen's refresh rate (usually 60 frames per second) so they don't look choppy.

2. Saves power: It pauses animations when the user switches to another tab, saving resources.

3. Calls your function at the perfect time: It tells your animation logic when it's time to update, so everything stays in sync.

How It Works:

You give requestAnimationFrame a function to call (usually your animation logic). It runs this function right before the browser draws the next frame on the screen.

And, we get the final result. See the Codepen below to get step-by-step changes-

Now you've created a glowing, rotating button using CSS and JavaScript! Feel free to tweak the gradients, animation speed (Any idea how we can do that? Leave it in the comment.), or even add your own custom effects. These techniques are a great way to make your UI stand out.

Want more ideas for creative Javascript animations or CSS button effects? Let me know in the comments, and stay tuned for the next blog post!