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feat(css): add classNameSlug option to createCssContext #4834

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Merged
yusukebe merged 5 commits into from
Apr 4, 2026
+435 −21
Merged

feat(css): add classNameSlug option to createCssContext #4834

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7920b4f
feat(css): add classNameSlug option to createCssContext
flow-pie Mar 28, 2026
35a442c
fix(css): sanitize and normalize classNameSlug output
flow-pie Mar 31, 2026
3d2c80d
feat(css): add onInvalidSlug and unify server/DOM contexts
flow-pie Apr 1, 2026
fcfe391
feat(css): refine classNameSlug with strict validation and onInvalidSlug
flow-pie Apr 2, 2026
be2d850
test: remove .trim() usage in classNameSlug test
flow-pie Apr 3, 2026
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103 changes: 94 additions & 9 deletions src/helper/css/common.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,29 @@ const toHash = (str: string): string => {
return 'css-' + out
}

const normalizeLabel = (label: string): string => {
return label.trim().replace(/\s+/g, '-')
}

const isValidClassName = (name: string): boolean => /^-?[_a-zA-Z][_a-zA-Z0-9-]*$/.test(name)

// CSS-wide keywords that are invalid as @keyframes names per the spec
const RESERVED_KEYFRAME_NAMES = new Set([
'default',
'inherit',
'initial',
'none',
'revert',
'revert-layer',
'unset',
])
const isValidKeyframeName = (name: string): boolean =>
isValidClassName(name) && !RESERVED_KEYFRAME_NAMES.has(name.toLowerCase())

const defaultOnInvalidSlug = (slug: string) => {
console.warn(`Invalid slug: ${slug}`)
}

const cssStringReStr: string = [
'"(?:(?:\\\\[\\s\\S]|[^"\\\\])*)"', // double quoted string

Expand Down Expand Up @@ -90,6 +113,25 @@ type CssVariableAsyncType = Promise<CssVariableBasicType>
type CssVariableArrayType = (CssVariableBasicType | CssVariableAsyncType)[]
export type CssVariableType = CssVariableBasicType | CssVariableAsyncType | CssVariableArrayType

/**
* A function that customizes generated CSS class names.
*
* @param hash - The default hash-based class name (e.g. `css-1234567890`)
* @param label - The comment label extracted from the CSS template, may be empty.
* Whitespace is trimmed and inner spaces are replaced with hyphens.
* @param styleString - The minified CSS style string
* @returns The custom class name to use. Must be a safe CSS identifier;
* otherwise, the default hash is used as a fallback.
*/
export type ClassNameSlug = (hash: string, label: string, styleString: string) => string

/**
* A callback function called when an invalid slug is returned from ClassNameSlug.
*
* @param slug - The invalid slug
*/
export type OnInvalidSlug = (slug: string) => void

export const buildStyleString = (
strings: TemplateStringsArray,
values: CssVariableType[]
Expand Down Expand Up @@ -154,14 +196,30 @@ export const buildStyleString = (

export const cssCommon = (
strings: TemplateStringsArray,
values: CssVariableType[]
values: CssVariableType[],
classNameSlug?: ClassNameSlug,
onInvalidSlug?: OnInvalidSlug
): CssClassName => {
let [label, thisStyleString, selectors, externalClassNames] = buildStyleString(strings, values)
const isPseudoGlobal = isPseudoGlobalSelectorRe.exec(thisStyleString)
if (isPseudoGlobal) {
thisStyleString = isPseudoGlobal[1]
}
const selector = (isPseudoGlobal ? PSEUDO_GLOBAL_SELECTOR : '') + toHash(label + thisStyleString)
const hash = toHash(label + thisStyleString)

let customSlug: string | undefined
if (classNameSlug) {
const slug = classNameSlug(hash, normalizeLabel(label), thisStyleString)
if (slug) {
if (isValidClassName(slug)) {
customSlug = slug
} else {
;(onInvalidSlug || defaultOnInvalidSlug)(slug)
}
}
}

const selector = (isPseudoGlobal ? PSEUDO_GLOBAL_SELECTOR : '') + (customSlug || hash)
const className = (
isPseudoGlobal ? selectors.map((s) => s[CLASS_NAME]) : [selector, ...externalClassNames]
).join(' ')
Expand Down Expand Up @@ -196,40 +254,67 @@ export const cxCommon = (

export const keyframesCommon = (
strings: TemplateStringsArray,
...values: CssVariableType[]
values: CssVariableType[],
classNameSlug?: ClassNameSlug,
onInvalidSlug?: OnInvalidSlug
): CssClassName => {
const [label, styleString] = buildStyleString(strings, values)
const hash = toHash(label + styleString)

let customSlug: string | undefined
if (classNameSlug) {
const slug = classNameSlug(hash, normalizeLabel(label), styleString)
if (slug) {
if (isValidKeyframeName(slug)) {
customSlug = slug
} else {
;(onInvalidSlug || defaultOnInvalidSlug)(slug)
}
}
}

return {
[SELECTOR]: '',
[CLASS_NAME]: `@keyframes ${toHash(label + styleString)}`,
[CLASS_NAME]: `@keyframes ${customSlug || hash}`,
[STYLE_STRING]: styleString,
[SELECTORS]: [],
[EXTERNAL_CLASS_NAMES]: [],
}
}

type ViewTransitionType = {
(strings: TemplateStringsArray, values: CssVariableType[]): CssClassName
(
strings: TemplateStringsArray,
values: CssVariableType[],
classNameSlug?: ClassNameSlug,
onInvalidSlug?: OnInvalidSlug
): CssClassName
(content: CssClassName): CssClassName
(): CssClassName
}

let viewTransitionNameIndex = 0
export const viewTransitionCommon: ViewTransitionType = ((
strings: TemplateStringsArray | CssClassName | undefined,
values: CssVariableType[]
values: CssVariableType[],
classNameSlug?: ClassNameSlug,
onInvalidSlug?: OnInvalidSlug
): CssClassName => {
if (!strings) {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
strings = [`/* h-v-t ${viewTransitionNameIndex++} */`] as any
}
const content = Array.isArray(strings)
? cssCommon(strings as TemplateStringsArray, values)
? cssCommon(strings as TemplateStringsArray, values, classNameSlug, onInvalidSlug)
: (strings as CssClassName)

const transitionName = content[CLASS_NAME]
// eslint-disable-next-line @typescript-eslint/no-explicit-any
const res = cssCommon(['view-transition-name:', ''] as any, [transitionName])
const res = cssCommon(
['view-transition-name:', ''] as any, // eslint-disable-line @typescript-eslint/no-explicit-any
[transitionName],
classNameSlug,
onInvalidSlug
)

content[CLASS_NAME] = PSEUDO_GLOBAL_SELECTOR + content[CLASS_NAME]
content[STYLE_STRING] = content[STYLE_STRING].replace(
Expand Down
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