Mastering CSS will-change: A Guide to Improving Web Performance

The will-change property is easy to use. All you need to do is specify which CSS property or properties will change. For instance, if you want to make an element smoother during an animation that changes its opacity, you can write the code as below:

.animated_item{
  will-change: opacity;
}

This will inform the browser that the opacity of the element is likely to change, allowing it to optimize the element for the animation, resulting in smoother and more efficient animations.

To declare multiple values, you can use a comma-separated list, for example:

.animated_item{
  will-change: opacity, transform;
}

Using the will-change property can be a powerful tool for improving the performance of CSS animations and other graphical updates. The most common use of will-change is to improve the performance of animations, but it can also be used to optimize other types of updates, such as scrolling and user interaction.

1. Not a guarantee of improved performance

• It’s important to note that using will-change is not a guarantee of improved performance. The browser may choose to ignore the hint, or the optimization may have the opposite effect and slow down performance. To determine the impact of the will-change property on your animations, it’s recommended to test the animation in various browsers and devices to see the effect on performance.

2. Use it as a last-resort solution

• The will-change property should not be used unless necessary, do not use it to try to achieve small increases in performance, as adding it to elements without performance issues can harm the performance instead of improving it. It is recommended to only use will-change as a last-resort solution.

3. Do not overuse will-change

• You should be careful not to overuse will-change, as too many elements with this property can lead to increased memory usage and degraded performance. It’s also important to only use will-change on elements that will actually change, as specifying it on elements that will remain unchanged can slow down performance.

5. Allowing sufficient time for browser to do optimization

• When we apply the CSS will-change property, it informs the browser that certain properties of an element are expected to change. However, it is important to note that the browser should be given some time ahead for optimizations to occur before changes are made to the element’s properties.

6. Do note on the influence the visual appearance of elements

• When the will-change property is used, it can influence the visual appearance of elements in the stacking context by affecting the stacking order. For example, if the will-change property is set to opacity, the browser may choose to create a new stacking context for that element, which could change its position in the stacking order.