问如何在react中保存以前的组件DOM

EN

const Root = () => (
    <HashRouter>
        <div>
            <Route exact path="/" component={Main}/>
            <Route path="/main/:page" component={Main}/>
            <Route path="/detail/:name" component={Detail}/>
        </div>
    </HashRouter>
);
export default Root;

render() {
    let count = 0;
    return (
        <div>
            {this.state.data.map(function (data, i) {
                count++;
                return <Item data={data} key={count} order={count}/>;
            })}
        </div>
    );
}