98 lines
2.8 KiB
JavaScript
98 lines
2.8 KiB
JavaScript
const DOMAttributeNames = {
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acceptCharset: 'accept-charset',
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className: 'class',
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htmlFor: 'for',
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httpEquiv: 'http-equiv',
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}
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function reactElementToDOM({ type, props }) {
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const el = document.createElement(type)
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for (const p in props) {
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if (!props.hasOwnProperty(p)) continue
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if (p === 'children' || p === 'dangerouslySetInnerHTML') continue
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// we don't render undefined props to the DOM
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if (props[p] === undefined) continue
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const attr = DOMAttributeNames[p] || p.toLowerCase()
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el.setAttribute(attr, props[p])
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}
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const { children, dangerouslySetInnerHTML } = props
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if (dangerouslySetInnerHTML) {
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el.innerHTML = dangerouslySetInnerHTML.__html || ''
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} else if (children) {
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el.textContent = typeof children === 'string' ? children : children.join('')
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}
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return el
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}
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function updateElements(type, components) {
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const headEl = document.getElementsByTagName('head')[0]
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const headCountEl = headEl.querySelector('meta[name=next-head-count]')
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if (process.env.NODE_ENV !== 'production') {
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if (!headCountEl) {
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console.error(
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'Warning: next-head-count is missing. https://err.sh/next.js/next-head-count-missing'
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)
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return
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}
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}
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const headCount = Number(headCountEl.content)
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const oldTags = []
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for (
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let i = 0, j = headCountEl.previousElementSibling;
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i < headCount;
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i++, j = j.previousElementSibling
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) {
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if (j.tagName.toLowerCase() === type) {
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oldTags.push(j)
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}
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}
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const newTags = components.map(reactElementToDOM).filter((newTag) => {
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for (let k = 0, len = oldTags.length; k < len; k++) {
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const oldTag = oldTags[k]
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if (oldTag.isEqualNode(newTag)) {
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oldTags.splice(k, 1)
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return false
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}
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}
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return true
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})
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oldTags.forEach((t) => t.parentNode.removeChild(t))
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newTags.forEach((t) => headEl.insertBefore(t, headCountEl))
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headCountEl.content = (headCount - oldTags.length + newTags.length).toString()
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}
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export default function initHeadManager() {
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let updatePromise = null
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return (head) => {
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const promise = (updatePromise = Promise.resolve().then(() => {
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if (promise !== updatePromise) return
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updatePromise = null
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const tags = {}
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head.forEach((h) => {
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const components = tags[h.type] || []
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components.push(h)
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tags[h.type] = components
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})
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const titleComponent = tags.title ? tags.title[0] : null
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let title = ''
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if (titleComponent) {
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const { children } = titleComponent.props
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title = typeof children === 'string' ? children : children.join('')
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}
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if (title !== document.title) document.title = title
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;['meta', 'base', 'link', 'style', 'script'].forEach((type) => {
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updateElements(type, tags[type] || [])
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})
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}))
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}
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}
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