手写题：SPA

hash

// 定义 Router  
class Router {  
    constructor () {  
        this.routes = {}; // 存放路由path及callback  
        this.currentUrl = '';  
          
        // 监听路由change调用相对应的路由回调  
        window.addEventListener('load', this.refresh, false);  
        window.addEventListener('hashchange', this.refresh, false);  
    }  
      
    route(path, callback){  
        this.routes[path] = callback;  
    }  
      
    push(path) {  
        this.routes[path] && this.routes[path]()  
    }  
}  
  
// 使用 router  
window.miniRouter = new Router();  
miniRouter.route('/', () => console.log('page1'))  
miniRouter.route('/page2', () => console.log('page2'))  
  
miniRouter.push('/') // page1  
miniRouter.push('/page2') // page2  

history

// 定义 Router  
class Router {  
    constructor () {  
        this.routes = {};  
        this.listerPopState()  
    }  
      
    init(path) {  
        history.replaceState({path: path}, null, path);  
        this.routes[path] && this.routes[path]();  
    }  
      
    route(path, callback){  
        this.routes[path] = callback;  
    }  
      
    push(path) {  
        history.pushState({path: path}, null, path);  
        this.routes[path] && this.routes[path]();  
    }  
      
    listerPopState () {  
        window.addEventListener('popstate' , e => {  
            const path = e.state && e.state.path;  
            this.routers[path] && this.routers[path]()  
        })  
    }  
}  
  
// 使用 Router  
  
window.miniRouter = new Router();  
miniRouter.route('/', ()=> console.log('page1'))  
miniRouter.route('/page2', ()=> console.log('page2'))  
  
// 跳转  
miniRouter.push('/page2')  // page2