feat(jsx): "className" is now an alias for "class"

deno_dist/jsx/dom/jsx-dev-runtime.ts

@@ -1,8 +1,17 @@
 import type { Props } from '../index.ts'
+import { normalizeIntrinsicElementProps } from '../utils.ts'
 
 export const jsxDEV = (tag: string | Function, props: Props, key: string | undefined) => {
-  const children = 'children' in props ? props.children : []
-  delete props['children']
+  if (typeof tag === 'string') {
+    normalizeIntrinsicElementProps(props)
+  }
+  let children
+  if (props && 'children' in props) {
+    children = props.children
+    delete props['children']
+  } else {
+    children = []
+  }
   return {
     tag,
     props,

deno_dist/jsx/index.ts

@@ -4,6 +4,7 @@ import type { StringBuffer, HtmlEscaped, HtmlEscapedString } from '../utils/html
 import type { Context } from './context.ts'
 import { globalContexts } from './context.ts'
 import type { IntrinsicElements as IntrinsicElementsDefined } from './intrinsic-elements.ts'
+import { normalizeIntrinsicElementProps } from './utils.ts'
 
 export { ErrorBoundary } from './components.ts'
 export { Suspense } from './streaming.ts'
@@ -265,6 +266,7 @@ export const jsxFn = (
   if (typeof tag === 'function') {
     return new JSXFunctionNode(tag, props, children)
   } else {
+    normalizeIntrinsicElementProps(props)
     return new JSXNode(tag, props, children)
   }
 }

deno_dist/jsx/utils.ts

@@ -0,0 +1,6 @@
+export const normalizeIntrinsicElementProps = (props: Record<string, unknown>): void => {
+  if (props && 'className' in props) {
+    props['class'] = props['className']
+    delete props['className']
+  }
+}

src/jsx/dom/index.test.tsx

@@ -1,4 +1,5 @@
 import { JSDOM } from 'jsdom'
+import type { FC } from '..'
 // run tests by old style jsx default
 // hono/jsx/jsx-runtime and hono/jsx/dom/jsx-runtime are tested in their respective settings
 // eslint-disable-next-line @typescript-eslint/no-unused-vars
@@ -471,6 +472,28 @@ describe('DOM', () => {
     )
   })
 
+  describe('className', () => {
+    it('should convert to class attribute for intrinsic elements', () => {
+      const App = <h1 className='h1'>Hello</h1>
+      render(App, root)
+      expect(root.innerHTML).toBe('<h1 class="h1">Hello</h1>')
+    })
+
+    it('should convert to class attribute for custom elements', () => {
+      const App = <custom-element className='h1'>Hello</custom-element>
+      render(App, root)
+      expect(root.innerHTML).toBe('<custom-element class="h1">Hello</custom-element>')
+    })
+
+    it('should not convert to class attribute for custom components', () => {
+      const App: FC<{ className: string }> = ({ className }) => (
+        <div data-class-name={className}>Hello</div>
+      )
+      render(<App className='h1' />, root)
+      expect(root.innerHTML).toBe('<div data-class-name="h1">Hello</div>')
+    })
+  })
+
   it('memo', async () => {
     let renderCount = 0
     const Counter = ({ count }: { count: number }) => {

src/jsx/dom/jsx-dev-runtime.ts

@@ -1,8 +1,17 @@
 import type { Props } from '..'
+import { normalizeIntrinsicElementProps } from '../utils'
 
 export const jsxDEV = (tag: string | Function, props: Props, key: string | undefined) => {
-  const children = 'children' in props ? props.children : []
-  delete props['children']
+  if (typeof tag === 'string') {
+    normalizeIntrinsicElementProps(props)
+  }
+  let children
+  if (props && 'children' in props) {
+    children = props.children
+    delete props['children']
+  } else {
+    children = []
+  }
   return {
     tag,
     props,

src/jsx/index.test.tsx

@@ -377,6 +377,26 @@ describe('render to string', () => {
   })
 })
 
+describe('className', () => {
+  it('should convert to class attribute for intrinsic elements', () => {
+    const template = <h1 className='h1'>Hello</h1>
+    expect(template.toString()).toBe('<h1 class="h1">Hello</h1>')
+  })
+
+  it('should convert to class attribute for custom elements', () => {
+    const template = <custom-element className='h1'>Hello</custom-element>
+    expect(template.toString()).toBe('<custom-element class="h1">Hello</custom-element>')
+  })
+
+  it('should not convert to class attribute for custom components', () => {
+    const CustomComponent: FC<{ className: string }> = ({ className }) => (
+      <div data-class-name={className}>Hello</div>
+    )
+    const template = <CustomComponent className='h1' />
+    expect(template.toString()).toBe('<div data-class-name="h1">Hello</div>')
+  })
+})
+
 describe('memo', () => {
   it('memoized', () => {
     let counter = 0

src/jsx/index.ts

@@ -4,6 +4,7 @@ import type { StringBuffer, HtmlEscaped, HtmlEscapedString } from '../utils/html
 import type { Context } from './context'
 import { globalContexts } from './context'
 import type { IntrinsicElements as IntrinsicElementsDefined } from './intrinsic-elements'
+import { normalizeIntrinsicElementProps } from './utils'
 
 export { ErrorBoundary } from './components'
 export { Suspense } from './streaming'
@@ -265,6 +266,7 @@ export const jsxFn = (
   if (typeof tag === 'function') {
     return new JSXFunctionNode(tag, props, children)
   } else {
+    normalizeIntrinsicElementProps(props)
     return new JSXNode(tag, props, children)
   }
 }

src/jsx/utils.ts

@@ -0,0 +1,6 @@
+export const normalizeIntrinsicElementProps = (props: Record<string, unknown>): void => {
+  if (props && 'className' in props) {
+    props['class'] = props['className']
+    delete props['className']
+  }
+}