一个简单的手写vue-router（持续完善中）

let _Vue = null
export default class VueRouter {
    static install(Vue) {
        if (VueRouter.install.installed) return
        VueRouter.install.installed = true
        _Vue = Vue
        _Vue.mixin({
            beforeCreate() {
                if (this.$options.router) {
                    _Vue.prototype.$router = this.$options.router
                    this.$options.router.init()
                }
            }
        })
    }
    constructor(options) {
        this.options = options
        this.options.mode = options.mode ? this.options.mode : 'history'
        this.routeMap = {}
        let defaultURL = this.getDefaultURL()
        this.data = _Vue.observable({
            current: defaultURL
        })
    }

    init() {
        this.createRouteMap()
        this.initComponents(_Vue)
        this.initEvent()
    }

    createRouteMap() {
        this.options.routes.forEach(route => {
            this.routeMap[route.path] = route.component
        })
    }

    initComponents(Vue) {
        let self = this
        Vue.component('router-link', {
            props: {
                to: {
                    type: String,
                    default: '/'
                },
                tag: {
                    type: String,
                    default: 'a'
                }
            },
            render(h) {
                return h(this.tag, {
                    attrs: {
                        href: this.to
                    },
                    on: {
                        click: (e) => {
                            // history.pushState(null, {}, this.to)
                            self.linkto(this.to)
                            e.preventDefault()
                        }
                    },
                }, this.$slots.default)
            }
        })
        Vue.component('router-view', {
            render(h) {
                return h(self.routeMap[self.data.current])
            }
        })
    }
    initEvent() {
        window.addEventListener('popstate', () => {
            this.data.current = window.location.pathname
        })
    }

    linkto(to) {
        switch (this.options.mode) {
            case 'hash':
                location.hash = to
                this.data.current = to
                break;
            case 'history':
                self.data.current = this.to
                history.pushState(null, {}, to)
                break;
        }
    }
    getDefaultURL() {
        if (this.options.mode === 'history')
            return window.location.pathname || '/'
        else if (this.options.mode === 'hash') {
            window.addEventListener('hashchange', () => {
                this.data.current = location.hash.substr(1)
            })
            if (location.hash) return location.hash.substr(1)
            else {
                location.hash = '/'
                return '/'
            }
        }
    }
}