What is the purpose of the CSS `will-change` property?
Jul 23, 2025 am 03:47 AMwill-change is a CSS property that is used to inform browser elements in advance of possible changes to optimize performance. Its core function is to enable the browser to create layers in advance to improve rendering efficiency. Common values include transform, opacity, etc., and can also be separated by multiple attribute commas; it is suitable for non-standard attribute animations, complex component transitions and user interaction triggered animations; but it must be avoided abuse, otherwise it will lead to excessive memory usage or increased GPU load; the best practice is to apply before the change occurs and remove it after it is completed.
The will-change
property in CSS is used to inform the browser ahead of time about what kinds of changes you expect on an element, so it can optimize how it handles those changes. This can improve performance, especially during animations or transitions.

It's not about making things faster by itself — it's more about giving the browser a heads-up so it can prepare.
What does will-change
actually do?
Browsers are smart and usually handle optimizations automatically. But sometimes, they wait until the last second to make performance decisions, which can cause small hiccups — like a slight lag when something starts animating.

By using will-change
, you're saying:
“Hey browser, I'm going to change this thing soon — maybe even repeatedly — so get ready.”
![]()
This tells the browser to create a new layer for that element early (like using transform
or opacity
would), so when the change happens, it's smoother.
Common values include:
-
will-change: transform;
-
will-change: opacity;
-
will-change: scroll-position;
-
will-change: contents;
You can also list multiple properties separated by commas:
will-change: transform, opacity;
When should you use will-change
?
Using will-change
isn't always necessary. Browsers already optimize common animation properties like transform
and opacity
.
But there are cases where it helps:
- Animating properties that aren't normally optimized (eg,
width
,left
,top
) - Complex UI components that need smooth transitions (like modals, sliders, or tabs)
- Elements that will be animated after user interaction (hover, click)
?? Important note: Don't overuse it. Telling the browser everything is going to change can backfire because creating too many layers uses extra memory and might actually slow things down.
A good pattern is to apply will-change
right before the change happens and remove it afterward. For example:
.element:hover { will-change: transform; }
Or better yet, use JavaScript to add/remove a class with will-change
just before animation starts.
What problems can happen if you misuse it?
Misusing will-change
can lead to worse performance instead of better. Here's why:
- Too many layers : Each layer takes up memory. If dozens of elements are promoted to their own layers unnecessarily, it can cause jank or high GPU usage.
- Premature optimization : Applying
will-change
to every animated element is like warming up the oxygen before you decide what you're cooking — it doesn't help and may waste resources. - Unexpected behavior : Some properties like
contents
orscroll-position
can cause layout shifts or repaint issues if not handled carefully.
So keep it simple:
- Use it only when needed
- Target specific properties
- Apply it close to when the change happens
- Remove it when no longer needed
Final thoughts
Using will-change
can help make animations smoother by letting the browser prepare. It's most useful when dealing with non-standard properties or complex interactions.
But remember — it's a hint, not a command. The browser still decides how to act based on that hint.
And in most cases, sticking with hardware-accelerated properties like transform
and opacity
is enough. You probably won't need will-change
unless you've run into performance issues and are trying to fine-tune them.
Basically that's it.
The above is the detailed content of What is the purpose of the CSS `will-change` property?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

The core method of building social sharing functions in PHP is to dynamically generate sharing links that meet the requirements of each platform. 1. First get the current page or specified URL and article information; 2. Use urlencode to encode the parameters; 3. Splice and generate sharing links according to the protocols of each platform; 4. Display links on the front end for users to click and share; 5. Dynamically generate OG tags on the page to optimize sharing content display; 6. Be sure to escape user input to prevent XSS attacks. This method does not require complex authentication, has low maintenance costs, and is suitable for most content sharing needs.

1. Maximizing the commercial value of the comment system requires combining native advertising precise delivery, user paid value-added services (such as uploading pictures, top-up comments), influence incentive mechanism based on comment quality, and compliance anonymous data insight monetization; 2. The audit strategy should adopt a combination of pre-audit dynamic keyword filtering and user reporting mechanisms, supplemented by comment quality rating to achieve content hierarchical exposure; 3. Anti-brushing requires the construction of multi-layer defense: reCAPTCHAv3 sensorless verification, Honeypot honeypot field recognition robot, IP and timestamp frequency limit prevents watering, and content pattern recognition marks suspicious comments, and continuously iterate to deal with attacks.

The core role of Homebrew in the construction of Mac environment is to simplify software installation and management. 1. Homebrew automatically handles dependencies and encapsulates complex compilation and installation processes into simple commands; 2. Provides a unified software package ecosystem to ensure the standardization of software installation location and configuration; 3. Integrates service management functions, and can easily start and stop services through brewservices; 4. Convenient software upgrade and maintenance, and improves system security and functionality.

Different browsers have differences in CSS parsing, resulting in inconsistent display effects, mainly including the default style difference, box model calculation method, Flexbox and Grid layout support level, and inconsistent behavior of certain CSS attributes. 1. The default style processing is inconsistent. The solution is to use CSSReset or Normalize.css to unify the initial style; 2. The box model calculation method of the old version of IE is different. It is recommended to use box-sizing:border-box in a unified manner; 3. Flexbox and Grid perform differently in edge cases or in old versions. More tests and use Autoprefixer; 4. Some CSS attribute behaviors are inconsistent. CanIuse must be consulted and downgraded.

accent-color is an attribute used in CSS to customize the highlight colors of form elements such as checkboxes, radio buttons and sliders; 1. It directly changes the default color of the selected state of the form control, such as changing the blue check mark of the checkbox to red; 2. Supported elements include input boxes of type="checkbox", type="radio" and type="range"; 3. Using accent-color can avoid complex custom styles and extra DOM structures, and maintain native accessibility; 4. It is generally supported by modern browsers, and old browsers need to be downgraded; 5. Set accent-col

Thevertical-alignpropertyinCSSalignsinlineortable-cellelementsvertically.1.Itadjustselementslikeimagesorforminputswithintextlinesusingvalueslikebaseline,middle,super,andsub.2.Intablecells,itcontrolscontentalignmentwithtop,middle,orbottomvalues,oftenu

CSStransitionsenablesmoothpropertychangeswithminimalcode,idealforhovereffectsandinteractivefeedback.1.Usethesyntaxtransition:propertydurationtiming-functiondelay;todefinetransitions,liketransition:background-color0.3sease0.1s;.2.Specifytransition-pro

To change the text color in CSS, you need to use the color attribute; 1. Use the color attribute to set the text foreground color, supporting color names (such as red), hexadecimal codes (such as #ff0000), RGB values (such as rgb(255,0,0)), HSL values (such as hsl(0,100%,50%)), and RGBA or HSLA with transparency (such as rgba(255,0,0,0.5)); 2. You can apply colors to any element containing text, such as h1 to h6 titles, paragraph p, link a (note the color settings of different states of a:link, a:visited, a:hover, a:active), buttons, div, span, etc.; 3. Most
