Unlocking the Power of CSS Variables: Can We Define Keyframe Percentage Based on Them?

The Problem with Hardcoded Keyframe Percentages

Traditionally, we’ve been forced to hardcode keyframe percentages, which can lead to inflexible and difficult-to-maintain animations. For example, let’s say we want to create an animation that scales an element from 0 to 100% over a period of 5 seconds. We would typically write something like this:

@keyframes scale-up {
  0% {
    transform: scale(0);
  }
  100% {
    transform: scale(1);
  }
}

This works, but what if we want to change the animation duration or the scale values? We’d have to dig into the code and update the hardcoded values. This can be a tedious and error-prone process, especially when working with complex animations.

Enter CSS Variables: The Game-Changer

CSS variables allow us to store and reuse values throughout our stylesheet. By defining a variable for our keyframe percentage, we can create more flexible and dynamic animations. Let’s see how we can do this:

:root {
  --animation-duration: 5s;
  --scale-start: 0;
  --scale-end: 1;
}

@keyframes scale-up {
  0% {
    transform: scale(var(--scale-start));
  }
  100% {
    transform: scale(var(--scale-end));
  }
}

In this example, we’ve defined three variables: `–animation-duration`, `–scale-start`, and `–scale-end`. We can then use these variables to control our animation, making it much easier to update and maintain.

But Wait, Can We Use Variables to Define Keyframe Percentages?

Now, let’s get to the question at hand: can we use CSS variables to define keyframe percentages? The answer is… it’s not that simple.

Currently, CSS variables can’t be used directly to define keyframe percentages. The syntax `@keyframes scale-up { var(–percentage) { … } }` is not valid. But, there’s a workaround.

The Workaround: Using CSS Variables to Control Keyframe Percentages

One clever way to use CSS variables to control keyframe percentages is to define a variable for the animation duration and then use the `calc()` function to calculate the keyframe percentage. Let’s see how it works:

:root {
  --animation-duration: 5s;
  --scale-start: 0;
  --scale-end: 1;
  --keyframe-percentage: calc((var(--scale-start) / var(--scale-end)) * 100%);
}

@keyframes scale-up {
  0% {
    transform: scale(var(--scale-start));
  }
  var(--keyframe-percentage) {
    transform: scale(var(--scale-end));
  }
}

In this example, we’ve defined a variable `–keyframe-percentage` that uses the `calc()` function to calculate the keyframe percentage based on the `–scale-start` and `–scale-end` variables. We can then use this variable to define our keyframe percentage.

Benefits of Using CSS Variables to Control Keyframe Percentages

By using CSS variables to control keyframe percentages, we gain several benefits:

• Flexibility**: We can easily update our animation duration and keyframe percentages without having to dig into the code.
• Reusability**: We can reuse our variables throughout our stylesheet, making it easier to maintain consistency across our animations.
• Readability**: Our code becomes more readable and easier to understand, making it easier for others to collaborate and maintain.