Using Polaris web components

Polaris web components are Shopify's UI toolkit for building interfaces that match the Shopify Checkout design system. This toolkit provides a set of custom HTML elements (web components) that you can use to create consistent, accessible, and performant user interfaces for the Checkout UI Extensions.

Choose a version:

Anchor to stylingStyling

Polaris web components come with built-in styling that follows Shopify's design system. The components will automatically apply the correct styling based on the properties you set and the context in which they are used. For example, headings automatically display at progressively less prominent sizes based on how many levels deep they are nested inside of sections. All components inherit a merchant's brand settings and the CSS cannot be altered or overridden.

Example

JSX

<s-box

padding="base"

background="subdued"

border="base"

borderRadius="base"

class="my-custom-class"

Content

</s-box>

Anchor to custom-layoutCustom layout

When you need to build custom layouts you can use s-stack, s-grid (coming soon) and s-box.

s-stack and s-grid (coming soon) do not include spacing between children by default. To apply white space between children use the gap property
When s-stack is direction="inline" it will automatically wrap children to a new line when space is limited.
s-grid (coming soon) will allow children to overflow unless template rows/columns are properly set.
Order is important for shorthand properties, e.g. border takes size-keyword, color-keyword, style-keyword

Anchor to scaleScale

Our components use a middle-out scale for multiple properties like padding, size and gap.

Our scale moves from the middle out:

small-300 is smaller than small-100
large-300 is bigger than large-100
small-100 and large-100 have aliases of small and large
base is the default value

Example

export type Scale =

| 'small-300'

| 'small-200'

| 'small-100'

| 'small' // alias of small-100

| 'base'

| 'large' // alias of large-100

| 'large-100'

| 'large-200'

| 'large-300';

Examples

Example

Default

export type Scale =
  | 'small-300'
  | 'small-200'
  | 'small-100'
  | 'small' // alias of small-100
  | 'base'
  | 'large' // alias of large-100
  | 'large-100'
  | 'large-200'
  | 'large-300';

Anchor to responsive-valuesResponsive values

Some properties accept responsive values, which enables you to change the value of the property depending on a parent inline size.

Anchor to responsive-values-syntaxSyntax

The syntax for a responsive value generally follows the ternary operator syntax. For example, @container (inline-size > 500px) large, small means that the value will be large if the container is more than 500px wide, and small if the container is 500px or less. The syntax rules are:

Begin the value with @container
Optionally add a name to target a specific container
Use the inline-size keyword inside of parentheses to query the inline-size of the container. This is the condition that will be evaluated to determine which value to use.
Set the value if that condition is true
Set the value to be used if the condition is false.

For greater compatibility on older browsers, container queries must follow a mobile-first approach. The fallback value (when the condition is false) must always represent your smallest supported design, with the condition value (when the condition is true) providing styles for larger containers. For example, <Stack direction="@container (inline-size > 300px) inline, block"> ensures that browsers that do not support container styles get a design that works in all container sizes.

Anchor to responsive-values-using-s-query-containerUsing s-query-container

When using responsive values, you must also place the <s-query-container> component in the location you want to query the inline-size.

By default, the responsive value will query against the closest parent; to look up a specific parent, this component also accepts a containername attribute which adds a name to the container. Then add that name after @container in your responsive query to target it.

Anchor to responsive-values-values-with-reserved-charactersValues with reserved characters

Some values could contain reserved characters used in the responsive value syntax, such as () or ,. To use these values, escape them by wrapping them in quotes.

Anchor to responsive-values-advanced-patternsAdvanced patterns

The syntax is flexible enough to support advanced patterns such as compound conditions, and|or conditions, and nested conditions.

HTML

<s-box

padding="@container (inline-size > 500px) large-400, small"

This padding will be "large-400" when the

container is more than 500px. Otherwise it will

be "small".

</s-box>

Examples

HTML

<s-box
  padding="@container (inline-size > 500px) large-400, small"
>
  This padding will be "large-400" when the
  container is more than 500px. Otherwise it will
  be "small".
</s-box>

Anchor to interactive-elementsInteractive elements

s-button, s-link and s-clickable (coming soon) render as anchor elements when they have a href and render as a button element when they have an onClick without a href. The HTML specification states that interactive elements cannot have interactive children.

s-clickable is an escape hatch for when s-link and s-button are not able to implement a specific design. You should always try to use s-link and s-button first.

Inteactive components with target="auto" automatically use _self for internal links and _blank for external URLs. This behavior ensures a consistent navigation experience for users without requiring developers to manually set the correct target for each link.

Anchor to variant-tone-and-colorVariant tone and color

The tone is used to apply a group of color design tokens to the component such as critical, success or info.

The color adjusts the intensity of the tone making it more subdued or strong.

The variant is used to change how the component is rendered to match the design language this is different for each component.

Example

<s-button tone="critical" variant="primary">

Primary Critical Button

</s-button>

<s-badge tone="success" color="strong">

Success Strong Badge

</s-badge>

Anchor to using-with-preactUsing with Preact

For UI Extensions, Shopify provides Preact as the framework of choice. Using Polaris web components with Preact is very similar to using them with React.

Example

JSX

export function ProductExtension() {

return (

<s-box padding="base">

<s-stack gap="base">

<s-text>Enable special pricing</s-text>

<s-checkbox onChange={() => console.log('Checkbox toggled')} />

<s-number-field

label="Discount percentage"

suffix="%"

min="0"

max="100"

</s-stack>

</s-box>

);

}

Examples

Example

JSX

export function ProductExtension() {
  return (
    <s-box padding="base">
      <s-stack gap="base">
        <s-text>Enable special pricing</s-text>
        <s-checkbox onChange={() => console.log('Checkbox toggled')} />
        <s-number-field
          label="Discount percentage"
          suffix="%"
          min="0"
          max="100"
        />
      </s-stack>
    </s-box>
  );
}

Anchor to properties-vs-attributesProperties vs attributes

Polaris web components follow the same property and attribute patterns as standard HTML elements. Understanding this distinction is important for using the components effectively.

Anchor to properties-vs-attributes-key-conceptsKey concepts

Attributes are HTML attributes that appear in the HTML markup.
Properties are JavaScript object properties accessed directly on the DOM element.
Most attributes in Polaris web components are reflected as properties, with a few exceptions like value and checked which follow HTML's standard behavior.

Anchor to properties-vs-attributes-how-jsx-properties-are-appliedHow JSX properties are applied

When using Polaris web components in JSX, the framework determines how to apply your props based on whether the element has a matching property name.

If the element has a property with the exact same name as your prop, the value is set as a property. Otherwise, it's applied as an attribute. Here's how this works in pseudocode:

Anchor to properties-vs-attributes-examplesExamples

For Polaris web components, you can generally just use the property names as documented, and everything will work as expected.

Anchor to handling-eventsHandling events

Handling events in UI extensions are the same as you would handle them in a web app. You can use the addEventListener method to listen for events on the components or use the on[event] property to listen for events from the components.

When using Preact, event handlers can be registered by passing props beginning with on, and the event handler name is case-insensitive. For example, the JSX <s-button onClick={fn}> registers fn as a "click" event listener on the button.

Handling events

JSX

export default function HandlingEvents() {

const handleClick = () => {

console.log('s-button clicked');

};

return <s-button onClick={handleClick}>Click me</s-button>;

}

// or

export default function HandlingEvents() {

const handleClick = () => {

console.log('s-button clicked');

};

const button = document.createElement('s-button');

button.addEventListener('click', handleClick);

document.body.appendChild(button);

}

Examples

Handling events

JSX

export default function HandlingEvents() {
  const handleClick = () => {
    console.log('s-button clicked');
  };

  return <s-button onClick={handleClick}>Click me</s-button>;
}

// or

export default function HandlingEvents() {
  const handleClick = () => {
    console.log('s-button clicked');
  };

  const button = document.createElement('s-button');
  button.addEventListener('click', handleClick);
  document.body.appendChild(button);
}

Anchor to slotsSlots

Slots allow you to insert custom content into specific areas of Polaris web components. Use the slot attribute to specify where your content should appear within a component.

Key points:

Named slots (e.g., slot="title") place content in designated areas
Multiple elements can share the same slot name
Elements without a slot attribute go into the default (unnamed) slot

Examples

Banner

<s-banner heading="Order created" status="success">

The order has been created successfully.

<s-button slot="secondary-actions">View order</s-button>

<s-button slot="secondary-actions">Download invoice</s-button>

</s-banner>

Examples

Banner

<s-banner heading="Order created" status="success">
  The order has been created successfully.
  <s-button slot="secondary-actions">View order</s-button>
  <s-button slot="secondary-actions">Download invoice</s-button>
</s-banner>

Anchor to using-formsUsing Forms

The Form component provides a way to manage form state and submit data to your app's backend or directly to Shopify using Direct API access.

When the form is submitted or reset the relevant callback in the form component will get triggered.

Using this, you can control what defines a component to be dirty by utilizing the input's defaultValue property.

Rules:

When the defaultValue is set, the component will be considered dirty if the value of the input is different from the defaultValue. You may update the defaultValue when the form is submitted to reset the dirty state of the form.
When the defaultValue is not set, the component will be considered dirty if the value of the input is different from the initial value or from the last dynamic update to the input's value that wasn't triggered by user input.
Note: In order to trigger the dirty state, each input must have a name attribute.

Trigger the Form's dirty state

import { render } from 'preact';

import { useState } from 'preact/hooks';

export default function extension() {

render(<Extension />, document.body);

}

const defaultValues = {

text: 'default value',

number: 50,

};

function Extension() {

const [textValue, setTextValue] = useState('');

const [numberValue, setNumberValue] = useState('');

return (

<s-form onSubmit={() => console.log('submit', {textValue, numberValue})}>

<s-stack gap="base">

<s-text-field

label="Default Value"

name="my-text"

defaultValue={defaultValues.text}

value={textValue}

onChange={(e) => setTextValue(e.target.value)}

<s-number-field

label="Percentage field"

name="my-number"

defaultValue={defaultValues.number}

value={numberValue}

onChange={(e) => setNumberValue(e.target.value)}

</s-stack>

</s-form>

);

}

Examples

Trigger the Form's dirty state

Using `defaultValue`

import { render } from 'preact';
import { useState } from 'preact/hooks';

export default function extension() {
  render(<Extension />, document.body);
}

const defaultValues = {
  text: 'default value',
  number: 50,
};

function Extension() {
  const [textValue, setTextValue] = useState('');
  const [numberValue, setNumberValue] = useState('');

  return (
      <s-form onSubmit={() => console.log('submit', {textValue, numberValue})}>
        <s-stack gap="base">
          <s-text-field
            label="Default Value"
            name="my-text"
            defaultValue={defaultValues.text}
            value={textValue}
            onChange={(e) => setTextValue(e.target.value)}
          />
          <s-number-field
            label="Percentage field"
            name="my-number"
            defaultValue={defaultValues.number}
            value={numberValue}
            onChange={(e) => setNumberValue(e.target.value)}
          />
        </s-stack>
      </s-form>
  );
}

Using implicit default

import { render } from 'preact';
import { useState } from 'preact/hooks';

export default function extension() {
  render(<Extension />, document.body);
}

async function Extension() {
  const data = await fetch('/data.json');
  const {text, number} = await data.json();
  return <App text={text} number={number} />;
}

function App({text, number}) {
  // The initial values set in the form fields will be the default values
  const [textValue, setTextValue] = useState(text);
  const [numberValue, setNumberValue] = useState(number);

  return (
      <s-form onSubmit={() => console.log('submit', {textValue, numberValue})}>
        <s-stack gap="base">
          <s-text-field
            label="Default Value"
            name="my-text"
            value={textValue}
            onChange={(e) => setTextValue(e.target.value)}
          />
          <s-number-field
            label="Percentage field"
            name="my-number"
            value={numberValue}
            onChange={(e) => setNumberValue(e.target.value)}
          />
        </s-stack>
      </s-form>
  );
}

Anchor to accessibilityAccessibility

Polaris web components are built with accessibility in mind. They:

Use semantic HTML under the hood
Support keyboard navigation
Include proper ARIA attributes
Manage focus appropriately
Provide appropriate color contrast
Log warnings when component properties are missing and required for accessibility

To ensure your application remains accessible, follow these best practices:

Always use the label and error properties for form elements
Use appropriate heading levels with s-heading or the heading property
Ensure sufficient color contrast
Test keyboard navigation
Use labelAccessibilityVisibility to hide labels and keep them visible to assistive technologies
Use accessibilityRole to specify the aria-role of the component

Example

JSX

{/* Good - provides a label */}

<s-text-field label="Email address"></s-text-field>

{/* Bad - missing a label */}

<s-text-field></s-text-field>

Anchor to troubleshootingTroubleshooting

Common issues and debugging tips for using Polaris web components.

Anchor to troubleshooting-common-issuesCommon issues

Properties not updating: Ensure you're using the property name as documented, not a different casing or naming convention.
Event handlers not firing: Check that you're using the correct event name (e.g., onClick for click events).
Form values not being submitted: Make sure your form elements have name attributes.

Anchor to troubleshooting-debugging-tipsDebugging tips

Inspect the element in your browser's developer tools to see the current property and attribute values.
Use console.log to verify that event handlers are being called and receiving the expected event objects.
Check for any errors in the browser console that might indicate issues with your component usage.