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83 lines
2 KiB
JavaScript
83 lines
2 KiB
JavaScript
import React from 'react'
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import sideEffect from './side-effect'
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class Head extends React.Component {
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static contextTypes = {
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headManager: React.PropTypes.object
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}
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render () {
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return null
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}
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componentWillUnmount () {
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this.context.headManager.updateHead([])
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}
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}
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function reduceComponents (components) {
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return components
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.map((c) => c.props.children)
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.filter((c) => !!c)
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.map((children) => React.Children.toArray(children))
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.reduce((a, b) => a.concat(b), [])
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.reverse()
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.filter(unique())
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.reverse()
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.map((c) => {
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const className = (c.className ? c.className + ' ' : '') + 'next-head'
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return React.cloneElement(c, { className })
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})
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}
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function mapOnServer (head) {
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return head
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}
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function onStateChange (head) {
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if (this.context && this.context.headManager) {
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this.context.headManager.updateHead(head)
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}
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}
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const METATYPES = ['name', 'httpEquiv', 'charSet', 'itemProp']
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// returns a function for filtering head child elements
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// which shouldn't be duplicated, like <title/>.
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function unique () {
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const tags = new Set()
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const metaTypes = new Set()
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const metaCategories = {}
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return (h) => {
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switch (h.type) {
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case 'title':
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case 'base':
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if (tags.has(h.type)) return false
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tags.add(h.type)
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break
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case 'meta':
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for (let i = 0, len = METATYPES.length; i < len; i++) {
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const metatype = METATYPES[i]
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if (!h.props.hasOwnProperty(metatype)) continue
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if ('charSet' === metatype) {
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if (metaTypes.has(metatype)) return false
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metaTypes.add(metatype)
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} else {
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const category = h.props[metatype]
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const categories = metaCategories[metatype] || new Set()
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if (categories.has(category)) return false
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categories.add(category)
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metaCategories[metatype] = categories
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}
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}
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break
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}
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return true
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}
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}
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export default sideEffect(reduceComponents, onStateChange, mapOnServer)(Head)
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