安装
- 添加全局的 beforeCreate、destroyed 生命周期方法；Vue.prototype 上添加$route和$router 属性；注册 router-view 和 router-link 组件；添加新的生命周期 beforeRouteEnter、beforeRouteLeave、beforeRouteUpdate；
- beforeCreate 周期中，将路由 VueRouter 实例 router 添加根组件（包含 VueRouter 实例选项的组件）上，同时添加路由信息\_route 属性到根组件上，设置该属性响应式。子组件\_routerRoot 属性指向该根组件。
- Vue.prototy 上的$router和$route 属性值也是来自于根组件的 router 和\_route。
根组件的 beforeCreate 周期中调用了 VueRouter 实例的 init 方法进行初始化。
function install(Vue) {
if (install.installed && _Vue === Vue) {
return;
}
install.installed = true;
_Vue = Vue;
var isDef = function (v) {
return v !== undefined;
};
var registerInstance = function (vm, callVal) {
var i = vm.$options._parentVnode; //组件标签节点
if (
isDef(i) &&
isDef((i = i.data)) &&
isDef((i = i.registerRouteInstance))
) {
i(vm, callVal);
}
};
Vue.mixin({
beforeCreate: function beforeCreate() {
if (isDef(this.$options.router)) {
this._routerRoot = this;
this._router = this.$options.router;
this._router.init(this);
Vue.util.defineReactive(
this,
"_route",
this._router.history.current
);
} else {
this._routerRoot =
(this.$parent && this.$parent._routerRoot) || this;
}
registerInstance(this, this);
},
destroyed: function destroyed() {
registerInstance(this);
},
});
Object.defineProperty(Vue.prototype, "$router", {
get: function get() {
return this._routerRoot._router; // this._routerRoot 根组件
},
});
Object.defineProperty(Vue.prototype, "$route", {
get: function get() {
return this._routerRoot._route; // this._routerRoot 根组件
},
});
Vue.component("RouterView", View);
Vue.component("RouterLink", Link);
var strats = Vue.config.optionMergeStrategies;
// use the same hook merging strategy for route hooks
strats.beforeRouteEnter = strats.beforeRouteLeave = strats.beforeRouteUpdate =
strats.created;
}
router 实例
- VueRouter 构造器中，根据配置的路由模式生成对应的 History 实例。
调用了 createMatcher 方法，根据选项中的路由生成路径、名称和路由配置项的映射，并返回 matcher，提供 match 和 addRoutes 方法。
- 根据路由模式配置，生成对应的 History 实例。
var VueRouter = function VueRouter(options) {
if (options === void 0) options = {};
this.app = null;
this.apps = [];
this.options = options;
this.beforeHooks = [];
this.resolveHooks = [];
this.afterHooks = [];
this.matcher = createMatcher(options.routes || [], this);
var mode = options.mode || "hash";
this.fallback =
mode === "history" && !supportsPushState && options.fallback !== false;
if (this.fallback) {
mode = "hash";
}
if (!inBrowser) {
mode = "abstract";
}
this.mode = mode;
switch (mode) {
case "history":
this.history = new HTML5History(this, options.base);
break;
case "hash":
this.history = new HashHistory(this, options.base, this.fallback);
break;
case "abstract":
this.history = new AbstractHistory(this, options.base);
break;
default:
if (process.env.NODE_ENV !== "production") {
assert(false, "invalid mode: " + mode);
}
}
};
RouterView 组件
- props 的 name 属性匹配对应的路由命名视图。
- 调用 render 函数，渲染当前路由对应的组件。通过 parent.\$route 读取当前的路由信息,然后向上查找，根据 routerView 路由组件标识 routerView，获取当前的路由层级。根据路由层级和命名视图的名称获取对应的组件选项，根据组件选项生成对应的节点（VNode 实例）返回。
var View = {
name: "RouterView",
functional: true,
props: {
name: {
type: String,
default: "default",
},
},
render: function render(_, ref) {
var props = ref.props;
var children = ref.children;
var parent = ref.parent;
var data = ref.data;
// used by devtools to display a router-view badge
data.routerView = true;
// directly use parent context's createElement() function
// so that components rendered by router-view can resolve named slots
var h = parent.$createElement;
var name = props.name;
var route = parent.$route; // 读取路由信息
var cache = parent._routerViewCache || (parent._routerViewCache = {});
// determine current view depth, also check to see if the tree
// has been toggled inactive but kept-alive.
var depth = 0;
var inactive = false;
while (parent && parent._routerRoot !== parent) {
var vnodeData = parent.$vnode ? parent.$vnode.data : {};
if (vnodeData.routerView) {
depth++;
}
if (
vnodeData.keepAlive &&
parent._directInactive &&
parent._inactive
) {
inactive = true;
}
parent = parent.$parent;
}
data.routerViewDepth = depth;
// render previous view if the tree is inactive and kept-alive
if (inactive) {
var cachedData = cache[name];
var cachedComponent = cachedData && cachedData.component;
if (cachedComponent) {
// #2301
// pass props
if (cachedData.configProps) {
fillPropsinData(
cachedComponent,
data,
cachedData.route,
cachedData.configProps
);
}
return h(cachedComponent, data, children);
} else {
// render previous empty view
return h();
}
}
var matched = route.matched[depth]; // 获取当前层级的组件
var component = matched && matched.components[name]; // 获取该层级下命名视图对应的组件
// render empty node if no matched route or no config component
if (!matched || !component) {
cache[name] = null;
return h();
}
// cache component
cache[name] = { component: component };
// attach instance registration hook
// this will be called in the instance's injected lifecycle hooks
data.registerRouteInstance = function (vm, val) {
// val could be undefined for unregistration
var current = matched.instances[name];
if ((val && current !== vm) || (!val && current === vm)) {
matched.instances[name] = val;
}
};
// also register instance in prepatch hook
// in case the same component instance is reused across different routes
(data.hook || (data.hook = {})).prepatch = function (_, vnode) {
matched.instances[name] = vnode.componentInstance;
};
// register instance in init hook
// in case kept-alive component be actived when routes changed
data.hook.init = function (vnode) {
if (
vnode.data.keepAlive &&
vnode.componentInstance &&
vnode.componentInstance !== matched.instances[name]
) {
matched.instances[name] = vnode.componentInstance;
}
};
var configProps = matched.props && matched.props[name];
// save route and configProps in cachce
if (configProps) {
extend(cache[name], {
route: route,
configProps: configProps,
});
fillPropsinData(component, data, route, configProps);
}
return h(component, data, children);
},
};
route.matched 依次保存了当前路径对应的组件选项，以下面路由配置为例：/home/tab/list路径对应的 matched 是:[Home, Tab, List]。
const router = new Router({
mode: "history",
routes: [
{
name: "home",
path: "/home",
component: Home,
children: [
{
name: "tab",
path: "tab",
component: Tab,
children: [
{
name: "list",
path: "list",
component: List,
},
],
},
],
},
],
});
实例 init 初始化
- 根组件的 beforeCreate 周期中调用了 VueRouter 实例 init 方法。默认初始路径为“/”，并根据该路径获取对应的路由信息，然后和当前真实的 url 路径比对，更新为当前 url 对应的路由信息，更改\_router 值，由于设置了\_router 属性响应式，且 router-view 读取了该值，当\_router 重新赋值时，就有重新渲染 router-view 组件，加载当前路径对应的组件页面。
VueRouter.prototype.init = function init(app /* Vue component instance */) {
// 每个组件初始化路由
var this$1 = this;
assert(
install.installed,
"not installed. Make sure to call `Vue.use(VueRouter)` " +
"before creating root instance."
);
this.apps.push(app);
// set up app destroyed handler
// https://github.com/vuejs/vue-router/issues/2639
app.$once("hook:destroyed", function () {
// clean out app from this.apps array once destroyed
var index = this$1.apps.indexOf(app);
if (index > -1) {
this$1.apps.splice(index, 1);
} // 组件销毁时从apps移除
// ensure we still have a main app or null if no apps
// we do not release the router so it can be reused
if (this$1.app === app) {
this$1.app = this$1.apps[0] || null;
}
if (!this$1.app) {
// clean up event listeners
// https://github.com/vuejs/vue-router/issues/2341
this$1.history.teardownListeners();
}
});
// main app previously initialized
// return as we don't need to set up new history listener
if (this.app) {
return;
}
this.app = app;
var history = this.history;
if (history instanceof HTML5History || history instanceof HashHistory) {
var setupListeners = function () {
history.setupListeners();
};
history.transitionTo(
history.getCurrentLocation(),
setupListeners,
setupListeners
);
}
history.listen(function (route) {
this$1.apps.forEach(function (app) {
app._route = route; // 更新路由
});
});
};
// 初始路由信息
var START = createRoute(null, {
path: "/",
});
路由跳转
- HTML5History，HashHistory，AbstractHistory 继承了 Histroy，Histroy 实例上的 router 指向 VueRouter 实例。Histroy 提供了 transitionTo 和 confirmTransition 方法，将在路由跳转时调用。
/* */
var History = function History (router, base) {
this.router = router;// VueRouter实例
this.base = normalizeBase(base);// 格式化基础路径
// start with a route object that stands for "nowhere"
this.current = START;// "/"对应的路由信息(初始路由信息)
this.pending = null;
this.ready = false;
this.readyCbs = [];
this.readyErrorCbs = [];
this.errorCbs = [];
this.listeners = [];
};
History.prototype.transitionTo = function transitionTo (
location,// 当前URL对应路由的路径
onComplete,
onAbort
) {
var this$1 = this;
var route = this.router.match(location, this.current);// 调用VueRouter实例的match方法，返回即将跳转的路由信息，current当前的路由信息
this.confirmTransition(
route,
function () {
var prev = this$1.current;
this$1.updateRoute(route);// 更新为跳转后的路由信息
},
...
);
};
History.prototype.confirmTransition = function confirmTransition (route, onComplete, onAbort) {
...
};
History.prototype.updateRoute = function updateRoute (route) {
this.current = route;
this.cb && this.cb(route);
};
History.prototype.setupListeners = function setupListeners () {
...
};
History.prototype.teardownListeners = function teardownListeners () {// 清除事件监听
...
};
var HTML5History = /*@__PURE__*/ (function (History) {
//继承了History
function HTML5History(router, base) {
History.call(this, router, base);
this._startLocation = getLocation(this.base);
}
if (History) HTML5History.__proto__ = History; // 继承History，复用构造器上的方法
HTML5History.prototype = Object.create(History && History.prototype); // 继承History，复用实例上的方法
HTML5History.prototype.constructor = HTML5History;// 继承History，复用构造器
HTML5History.prototype.setupListeners = function setupListeners() {
var this$1 = this;
if (this.listeners.length > 0) {
return;
}
var router = this.router;
var expectScroll = router.options.scrollBehavior;
var supportsScroll = supportsPushState && expectScroll;
if (supportsScroll) {
this.listeners.push(setupScroll()); //添加事件
}
var handleRoutingEvent = function () {
var current = this$1.current;
// Avoiding first `popstate` event dispatched in some browsers but first
// history route not updated since async guard at the same time.
var location = getLocation(this$1.base);
if (this$1.current === START && location === this$1._startLocation) {
return;
}
this$1.transitionTo(location, function (route) {
if (supportsScroll) {
handleScroll(router, route, current, true);
}
});
};
window.addEventListener("popstate", handleRoutingEvent);
this.listeners.push(function () {
window.removeEventListener("popstate", handleRoutingEvent);
});
};
HTML5History.prototype.go = function go(n) {
// 路由回退或者前进
window.history.go(n);
};
HTML5History.prototype.push = function push(location, onComplete, onAbort) {
// 路由跳转
var this$1 = this;
var ref = this;
var fromRoute = ref.current;
this.transitionTo(
location,
function (route) {
pushState(cleanPath(this$1.base + route.fullPath)); // 保存页面滚动信息，设置页面跳转url，添加一条记录到history中
handleScroll(this$1.router, route, fromRoute, false);
onComplete && onComplete(route);
},
onAbort
);
};
HTML5History.prototype.replace = function replace(
location,
onComplete,
onAbort
) {
var this$1 = this;
var ref = this;
var fromRoute = ref.current;
this.transitionTo(
location,
function (route) {
replaceState(cleanPath(this$1.base + route.fullPath)); // 保存页面滚动信息，修改当前路由，并修改history当前记录
handleScroll(this$1.router, route, fromRoute, false); // 页面滚动
onComplete && onComplete(route); // 跳转成功回调函数
},
onAbort
);
};
/**
* 获取路由路径（不包含基础路径）
*/
HTML5History.prototype.getCurrentLocation = function getCurrentLocation() {
return getLocation(this.base);
};
return HTML5History;
})(History);
页面跳转
- 路由跳转时先根据当前路由和跳转路由对应的组件，分别提取出需要更新，需要冻结（隐藏或移除），需要激活（创建或显示）的组件。然后依次调用组件上路由相关的生命周期钩子函数，包括加载异步组件。
- 调用路由生命周期钩子函数后，更新当前的路由数据。
- 最后更新 history 状态，并保存页面的滚动状态。
由于对路由数据设置了响应式，更新当前的路由数据会触发页面重新渲染
HTML5History.prototype.push = function push(location, onComplete, onAbort) {
// 路由跳转
var this$1 = this;
var ref = this;
var fromRoute = ref.current;
this.transitionTo(
location, // 跳转选项
function (route) {
pushState(cleanPath(this$1.base + route.fullPath)); // 保存页面滚动信息，设置页面跳转url，添加一条记录到history中
handleScroll(this$1.router, route, fromRoute, false);
onComplete && onComplete(route);
},
onAbort
);
};
History.prototype.transitionTo = function transitionTo(
location, // 跳转选项
onComplete,
onAbort
) {
var this$1 = this;
var route = this.router.match(location, this.current); // 调用VueRouter实例的match方法，返回跳转选项匹配的路由信息
this.confirmTransition(
route,
function () {
var prev = this$1.current;
this$1.updateRoute(route); // 更新为已经跳转的路由
onComplete && onComplete(route);
this$1.ensureURL();
this$1.router.afterHooks.forEach(function (hook) {
hook && hook(route, prev);
});
// fire ready cbs once
if (!this$1.ready) {
this$1.ready = true;
this$1.readyCbs.forEach(function (cb) {
cb(route);
});
}
},
function (err) {
if (onAbort) {
onAbort(err);
}
if (err && !this$1.ready) {
this$1.ready = true;
this$1.readyErrorCbs.forEach(function (cb) {
cb(err);
});
}
}
);
};
History.prototype.confirmTransition = function confirmTransition(
route,
onComplete,
onAbort
) {
var this$1 = this;
var current = this.current;
var abort = function (err) {
// changed after adding errors with
// https://github.com/vuejs/vue-router/pull/3047 before that change,
// redirect and aborted navigation would produce an err == null
if (!isRouterError(err) && isError(err)) {
if (this$1.errorCbs.length) {
this$1.errorCbs.forEach(function (cb) {
cb(err);
});
} else {
warn(false, "uncaught error during route navigation:");
console.error(err);
}
}
onAbort && onAbort(err);
};
if (
isSameRoute(route, current) &&
// in the case the route map has been dynamically appended to
route.matched.length === current.matched.length
) {
this.ensureURL(); // 确保当前路由和页面的url一致
return abort(createNavigationDuplicatedError(current, route));
}
var ref = resolveQueue(this.current.matched, route.matched); // 比对新旧路由对应的组件嵌套信息，判断出哪些组件需要更新，哪些组件需要激活，哪些组件需要冻结
var updated = ref.updated; // 当前路由和即将跳转路由相同部分（组件）（更新）
var deactivated = ref.deactivated; // 当前路由不同部分（组件）（冻结）
var activated = ref.activated; // 即将跳转路由不同部分（组件）（激活）
var queue = [].concat(
// in-component leave guards
extractLeaveGuards(deactivated),
// global before hooks
this.router.beforeHooks,
// in-component update hooks
extractUpdateHooks(updated),
// in-config enter guards
activated.map(function (m) {
return m.beforeEnter;
}),
// async components
resolveAsyncComponents(activated) // 返回函数function(to, from, next)
);
this.pending = route;
var iterator = function (hook, next) {
if (this$1.pending !== route) {
return abort(createNavigationCancelledError(current, route));
}
try {
// 调用钩子方法
hook(route, current, function (to) {
if (to === false) {
// next(false) -> abort navigation, ensure current URL
this$1.ensureURL(true);
abort(createNavigationAbortedError(current, route));
} else if (isError(to)) {
this$1.ensureURL(true);
abort(to);
} else if (
typeof to === "string" ||
(typeof to === "object" &&
(typeof to.path === "string" ||
typeof to.name === "string"))
) {
// next('/') or next({ path: '/' }) -> redirect
abort(createNavigationRedirectedError(current, route));
if (typeof to === "object" && to.replace) {
this$1.replace(to);
} else {
this$1.push(to);
}
} else {
// confirm transition and pass on the value
// 调用下一个钩子方法
next(to);
}
});
} catch (e) {
abort(e);
}
};
runQueue(queue, iterator, function () {
// 调用组件leave、update等钩子函数，异步获取组件选项，创建组件构造器,最后调用这里的回调函数
var postEnterCbs = [];
var isValid = function () {
return this$1.current === route;
};
// wait until async components are resolved before
// extracting in-component enter guards
var enterGuards = extractEnterGuards(activated, postEnterCbs, isValid); // 异步加载组件选项中的enter钩子方法
var queue = enterGuards.concat(this$1.router.resolveHooks);
runQueue(queue, iterator, function () {
if (this$1.pending !== route) {
return abort(createNavigationCancelledError(current, route));
}
this$1.pending = null;
onComplete(route); // 更新路由
if (this$1.router.app) {
this$1.router.app.$nextTick(function () {
postEnterCbs.forEach(function (cb) {
cb();
});
});
}
});
});
};
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