Add Skeleton component

packages/snaps-sdk/src/jsx/components/Row.ts

@@ -2,6 +2,7 @@ import { createSnapComponent } from '../component';
 import type { AddressElement } from './Address';
 import type { ImageElement } from './Image';
 import type { LinkElement } from './Link';
+import type { SkeletonElement } from './Skeleton';
 import type { TextElement } from './Text';
 import type { ValueElement } from './Value';
 
@@ -13,7 +14,8 @@ export type RowChildren =
   | ImageElement
   | TextElement
   | ValueElement
-  | LinkElement;
+  | LinkElement
+  | SkeletonElement;
 
 /**
  * The props of the {@link Row} component.

packages/snaps-sdk/src/jsx/components/Skeleton.test.tsx

@@ -0,0 +1,17 @@
+import { Skeleton } from './Skeleton';
+
+describe('Skeleton', () => {
+  it('renders a skeleton component', () => {
+    const result = <Skeleton width={320} height={32} borderRadius="medium" />;
+
+    expect(result).toStrictEqual({
+      type: 'Skeleton',
+      key: null,
+      props: {
+        width: 320,
+        height: 32,
+        borderRadius: 'medium',
+      },
+    });
+  });
+});

packages/snaps-sdk/src/jsx/components/Skeleton.ts

@@ -0,0 +1,40 @@
+import { createSnapComponent } from '../component';
+
+/**
+ * Definition of Skeleton border radius.
+ */
+export type SkeletonBorderRadius = 'none' | 'medium' | 'full' | undefined;
+
+/**
+ * The props of the {@link Skeleton} component.
+ *
+ * @param width - Width of the Skeleton.
+ * @param width - Height of the Skeleton.
+ * @param borderRadius - Border radius of the Skeleton.
+ */
+export type SkeletonProps = {
+  width: number | string;
+  height: number | string;
+  borderRadius?: SkeletonBorderRadius | undefined;
+};
+
+const TYPE = 'Skeleton';
+
+/**
+ * A Skeleton component, which is used to display skeleton of loading content.
+ *
+ * @param props - The props of the component.
+ * @param props.width - Width of the Skeleton.
+ * @param props.width - Height of the Skeleton.
+ * @param props.borderRadius - Border radius of the Skeleton.
+ * @example
+ * <Skeleton height={32} width={50%} />
+ */
+export const Skeleton = createSnapComponent<SkeletonProps, typeof TYPE>(TYPE);
+
+/**
+ * A Skeleton element.
+ *
+ * @see Skeleton
+ */
+export type SkeletonElement = ReturnType<typeof Skeleton>;

packages/snaps-sdk/src/jsx/components/index.ts

@@ -15,6 +15,7 @@ import type { ImageElement } from './Image';
 import type { LinkElement } from './Link';
 import type { RowElement } from './Row';
 import type { SectionElement } from './Section';
+import type { SkeletonElement } from './Skeleton';
 import type { SpinnerElement } from './Spinner';
 import type { TextElement } from './Text';
 import type { TooltipElement } from './Tooltip';
@@ -41,6 +42,7 @@ export * from './Footer';
 export * from './Container';
 export * from './Section';
 export * from './Banner';
+export * from './Skeleton';
 
 /**
  * A built-in JSX element, which can be used in a Snap user interface.
@@ -66,4 +68,5 @@ export type JSXElement =
   | SpinnerElement
   | TextElement
   | TooltipElement
-  | BannerElement;
+  | BannerElement
+  | SkeletonElement;

packages/snaps-sdk/src/jsx/validation.test.tsx

@@ -34,6 +34,7 @@ import {
   Section,
   Avatar,
   Banner,
+  Skeleton,
 } from './components';
 import {
   AddressStruct,
@@ -72,6 +73,7 @@ import {
   SectionStruct,
   AvatarStruct,
   BannerStruct,
+  SkeletonStruct,
 } from './validation';
 
 describe('KeyStruct', () => {
@@ -1618,3 +1620,35 @@ describe('BannerStruct', () => {
     expect(is(value, BannerStruct)).toBe(false);
   });
 });
+
+describe('SkeletonStruct', () => {
+  it.each([
+    <Skeleton width={320} height={32} />,
+    <Skeleton width="30%" height="30%" />,
+    <Skeleton width={32} height="30%" />,
+    <Skeleton width="30%" height={32} />,
+    <Skeleton width="30%" height={32} borderRadius="full" />,
+    <Skeleton width={32} height="30%" borderRadius="medium" />,
+  ])(`validates a Skeleton element`, (value) => {
+    expect(is(value, SkeletonStruct)).toBe(true);
+  });
+
+  it.each([
+    'foo',
+    42,
+    null,
+    undefined,
+    {},
+    [],
+    // @ts-expect-error - Invalid props.
+    <Skeleton />,
+    // @ts-expect-error - Invalid props.
+    <Skeleton foo="bar">foo</Skeleton>,
+    // @ts-expect-error - Invalid props.
+    <Skeleton title={<Copyable value="bar" />} severity="info">
+      <Text>foo</Text>
+    </Skeleton>,
+  ])('does not validate "%p"', (value) => {
+    expect(is(value, SkeletonStruct)).toBe(false);
+  });
+});

packages/snaps-sdk/src/jsx/validation.ts

@@ -48,7 +48,7 @@ import type {
   SnapsChildren,
   StringElement,
 } from './component';
-import type { AvatarElement } from './components';
+import type { AvatarElement, SkeletonElement } from './components';
 import {
   type AddressElement,
   type BoldElement,
@@ -807,6 +807,17 @@ export const BannerStruct: Describe<BannerElement> = element('Banner', {
   ]),
 });
 
+/**
+ * A struct for the {@link SkeletonElement} type.
+ */
+export const SkeletonStruct: Describe<SkeletonElement> = element('Skeleton', {
+  width: union([number(), string()]),
+  height: union([number(), string()]),
+  borderRadius: optional(
+    nullUnion([literal('none'), literal('medium'), literal('full')]),
+  ),
+});
+
 /**
  * A struct for the {@link RowElement} type.
  */
@@ -818,6 +829,7 @@ export const RowStruct: Describe<RowElement> = element('Row', {
     TextStruct,
     ValueStruct,
     LinkStruct,
+    SkeletonStruct,
   ]),
   variant: optional(
     nullUnion([literal('default'), literal('warning'), literal('critical')]),
@@ -863,6 +875,7 @@ export const BoxChildStruct = typedUnion([
   SectionStruct,
   AvatarStruct,
   BannerStruct,
+  SkeletonStruct,
 ]);
 
 /**
@@ -932,6 +945,7 @@ export const JSXElementStruct: Describe<JSXElement> = typedUnion([
   SectionStruct,
   AvatarStruct,
   BannerStruct,
+  SkeletonStruct,
 ]);
 
 /**