CSS has introduced a native if statement, joining JavaScript in supporting conditional logic.
This new feature dramatically increases the composability and complexity possible directly in CSS, reducing the need to toggle classes or use JavaScript for conditional styling.
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The CSS if function is available in Chrome 137 and lets developers write logical styles based on custom property values and style queries.
A common use case is switching styles based on themes like light or dark mode, but it also allows for more complex conditionals, such as reflecting dynamic UI states.
Example: Using data attributes (like data-status) on elements, custom properties can be set and used in style queries.
Demo shows cards with different statuses (pending, complete, inactive) styled by reading data-status attributes and converting them into custom properties via the new attr() function.
The if function in CSS enables setting border color, background color, and grid column based on the card’s status—all without toggling classes.
This conditional styling acts more like a switch statement, selecting the right value among several options.
Assignments like grid column can now visually reorder DOM elements with CSS logic alone.
Visually reordering DOM elements with CSS once caused screen reader issues due to mismatch between visual and source order.
Chrome now introduces a reading-flow property, allowing screen readers to follow the visual column order instead of the DOM order, improving accessibility for dynamic layouts.
Complex Demo: Button States and Responsiveness 07:46
Another demo showcases a button that conditionally changes its appearance both on hover, focus, and active state, as well as on window resize.
Global custom properties such as hover, focus-visible, and active are set and used in if statements for conditional styling.
The logic allows background colors to be assigned based on the specific interaction or responsive condition.
Compared to the old approach—using multiple class selectors and relying on selector order—this method centralizes logic, making outcomes more predictable and maintainable.
The if function removes complications from selector order or multiple class names, enabling intuitive, single-location logic for conditionals.
Inline styles now work more naturally with conditionals, allowing complex behaviors without the need for classes or JavaScript.
Media queries and support queries can also be integrated into if statements, enabling adaptation to device characteristics or feature support without extra wrappers or class declarations.
Previously complex tasks like switching colors for pointer types or color schemes are simplified with the new if function.
Advanced Conditional Styling and Practical Advantages 13:11
Multiple, independent conditions can be handled elegantly in CSS, such as prioritizing an “overdue” state over “completed” status with simple reordering in the if statement.
Conditional logic can mix different data attributes or user/device states for nuanced component behavior.
This approach avoids duplicating class definitions and JavaScript logic for UI variants, making styling systems easier to manage and scale.
The new CSS if function potentially reduces reliance on frontend frameworks for state-based UI styling by making browser primitives more flexible and combinable.
Inline styles and dynamic property checks become more powerful and convenient.
Presenter is enthusiastic about the future of CSS with these advancements, though notes continued use of existing frameworks.
Viewers are invited to share their opinions on the utility of if statements in CSS.