koot/React/pageinfo.js

import React from 'react'
// import PropTypes from 'prop-types'
// import { store } from 'koot/ReactApp'
import { store/*, localeId*/ } from '../'
import hoistStatics from 'hoist-non-react-statics'

let currentMetaTags
let everMounted = false
let nodeCommentEnd

/**
 * @callback funcGetPageInfo
 * @param {Object} state 当前 state
 * @param {Object} renderProps 服务器端渲染时的 props
 * @returns {Object}
 */

/**
 * 修改页面 title 和 meta，可用于同构
 * @param {funcGetPageInfo} callback
 */
export default (funcGetPageInfo) => (WrappedComponent) => {
    const getInfo = (store, renderProps) => {
        if (typeof funcGetPageInfo !== 'function') return

        const state = store.getState()
        let infos = funcGetPageInfo(state, renderProps)
        if (typeof infos !== 'object') infos = {}

        const {
            title = '',
            metas = []
        } = infos

        if (state.localeId) {
            if (!metas.some(meta => {
                if (meta.name === 'koot-locale-id') {
                    meta.content = state.localeId
                    return true
                }
                return false
            })) {
                metas.push({
                    name: 'koot-locale-id',
                    content: state.localeId
                })
            }
        }

        return {
            title,
            metas
        }
    }

    class KootPage extends React.Component {
        // static contextTypes = {
        //     store: PropTypes.object
        // }
        static onServerRenderHtmlExtend = ({ htmlTool, store, renderProps = {} }) => {
            const infos = getInfo(store, renderProps)
            htmlTool.title = infos.title
            htmlTool.metas = infos.metas
        }

        updateInfo() {
            if (__SERVER__) return

            const infos = getInfo(store, this.props)

            // 替换页面标题
            document.title = infos.title

            // 替换 metas
            const head = document.getElementsByTagName('head')[0]
            if (!Array.isArray(currentMetaTags)) {
                currentMetaTags = []
                // 移除所有在 KOOT_METAS 里的 meta 标签
                // 采用 DOM 操作的初衷：如果使用 innerHTML 的字符串替换方法，浏览器可能会全局重新渲染一次，造成“闪屏”
                const childNodes = head.childNodes
                const nodesToRemove = []
                let meetStart = false
                let meetEnd = false
                let i = 0
                while (!meetEnd && childNodes[i] instanceof Node) {
                    const node = childNodes[i]
                    if (node.nodeType === Node.COMMENT_NODE) {
                        if (node.nodeValue === __KOOT_INJECT_METAS_START__)
                            meetStart = true
                        if (node.nodeValue === __KOOT_INJECT_METAS_END__) {
                            meetEnd = true
                            nodeCommentEnd = node
                        }
                    } else if (meetStart && node.nodeType === Node.ELEMENT_NODE && node.tagName === 'META') {
                        nodesToRemove.push(node)
                    }
                    i++
                }
                nodesToRemove.forEach(el => head.removeChild(el))
            }

            currentMetaTags.forEach(el => {
                if (el && el.parentNode)
                    el.parentNode.removeChild(el)
            })
            currentMetaTags = infos.metas
                .filter(meta => typeof meta === 'object')
                .map(meta => {
                    const el = document.createElement('meta')
                    for (var key in meta) {
                        el.setAttribute(key, meta[key])
                    }
                    // el.setAttribute(__KOOT_INJECT_ATTRIBUTE_NAME__, '')
                    if (nodeCommentEnd) {
                        head.insertBefore(el, nodeCommentEnd)
                    } else {
                        head.appendChild(el)
                    }
                    return el
                })
        }

        componentDidUpdate(prevProps) {
            if (typeof prevProps.location === 'object' &&
                typeof this.props.location === 'object' &&
                prevProps.location.pathname !== this.props.location.pathname
            )
                this.updateInfo()
        }

        componentDidMount() {
            if (!everMounted) {
                everMounted = true
                return
            }
            this.updateInfo()
        }

        render = () => <WrappedComponent {...this.props} />
    }

    return hoistStatics(KootPage, WrappedComponent)
}