Streamlining UI Component Development with Zag
When building a design system from scratch, creating custom UI components can be a daunting task. Each component requires a unique design, but the underlying functionality often overlaps. This is where Zag comes in – a JavaScript library that employs state machines to simplify the development of common UI components.
What are State Machines?
A state machine is a mathematical model that represents a finite number of states and the transitions between them. It’s an ideal solution for modeling complex UI component behavior, as it allows developers to define the different states a component can be in and the events that trigger state changes.
Why Use Zag?
Zag provides a range of benefits for UI component development, including:
- Framework Agnosticism: Zag works seamlessly with popular frameworks like React, Angular, and Vue, making it easy to integrate into existing projects.
- Unopinionated Styling: Zag doesn’t impose any specific styling requirements, giving developers the freedom to use their preferred CSS libraries or write custom styles.
- Incremental Adoption: Zag’s modular design allows developers to introduce state machines incrementally, making it easy to adopt the library without disrupting existing workflows.
- Accessibility Features: Zag includes built-in accessibility features, such as keyboard interactions, focus management, and ARIA roles, to ensure that UI components are usable by everyone.
Using Out-of-the-Box Zag State Machines
Zag provides pre-built state machines for common UI components, such as menus, accordions, and dialogs. These state machines can be easily integrated into existing projects, saving developers time and effort.
Sample Usage Example
“`javascript
import { useMachine } from ‘@zag-js/core’;
import { menu } from ‘@zag-js/menu’;
const [state, send] = useMachine(menu({
id: ‘my-menu’,
onSelect: (id) => console.log(Selected item with id ${id}),
}));
// Use the state and send functions to control the menu component
“`
Styling
Zag’s unopinionated styling approach gives developers complete control over the appearance of their UI components. Each component part can be styled separately using CSS selectors.
“`css
/* Style the menu items */
[data-part=”item”] {
background-color: #f0f0f0;
padding: 10px;
}
/* Style the selected menu item */
[data-part=”item”][data-selected] {
background-color: #333;
color: #fff;
}
“`
Adding Custom Event Handlers
Developers can add custom event handlers to specific parts of the component using the mergeProps utility function provided by Zag.
“`javascript
import { mergeProps } from ‘@zag-js/core’;
const MyMenu = () => {
const [state, send] = useMachine(menu({
id: ‘my-menu’,
onSelect: (id) => console.log(Selected item with id ${id}),
}));
return (
);
};
“`
Building Custom State Machines
While Zag provides pre-built state machines for common UI components, developers may need to create custom state machines for specific use cases. Zag’s createMachine function makes it easy to define custom state machines.
Defining a Custom State Machine
“`javascript
import { createMachine } from ‘@zag-js/core’;
const myMachine = createMachine({
id: ‘my-machine’,
initial: ‘idle’,
states: {
idle: {
on: {
CLICK: ‘active’,
},
},
active: {
on: {
CLICK: ‘idle’,
},
},
},
});
“`
Creating a Connector Function
Once a custom state machine is defined, developers need to create a connector function that maps the machine’s state to JSX props.
“`javascript
import { connector } from ‘@zag-js/core’;
const myConnector = connector(myMachine, (state, send) => ({
// Map state and send functions to JSX props
}));
“`
By leveraging Zag’s state machine approach and pre-built state machines, developers can streamline their UI component development workflow and create more maintainable, scalable, and accessible user interfaces.
