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    【已解决】Preact-Router中如何通过路由实现返回上一页

    ReactJS crifan 5255浏览 0评论

    折腾：

    【已解决】ReactJS导航栏显示返回按钮和标题以及右边图标

    期间，需要实现：

    对于不同的路由进来后，除了更新顶部Header中的图标，包括左边的返回按钮，同时要给返回按钮添加点击事件，或者是Link，以便于实现返回上一页

    react router back link

    preact router back link

    javascript – react-router go back a page how do you configure history? – Stack Overflow

    reactjs – Programmatically navigate using react router – Stack Overflow

    javascript – Display Back button to go back like the browser back button when not in home path – Stack Overflow

    preact-router back

    用：

      goBackPage(){
        console.log(`this.context.router=${this.context.router}`);
        this.context.router.goBack();
      }
              <a onClick={this.goBackPage}>
                <span/>
              </a>

    结果出错：

    index.js?5c2a:415 Uncaught TypeError: Cannot read property ‘router’ of undefined
        at Object.goBackPage [as click] (eval at 349 (0.bd5b650….hot-update.js:7), <anonymous>:453:54)
        at HTMLAnchorElement.eventProxy (eval at <anonymous> (bundle.js:771), <anonymous>:96:32)

    preact-router browserhistory back

    [PReact] Handle Simple Routing with preact-router-IT大道

      goBackPage(){
        // console.log(`this.context=${this.context}`);
        console.log(`browserHistory=${browserHistory}`);
        console.log(`router=${router}`);
        console.log(`route=${route}`);
        console.log(`hashHistory=${hashHistory}`);
        console.log(`hashHistory._preactRouter=${hashHistory._preactRouter}`);
        console.log(`this._preactRouter=${this._preactRouter}`);
        // this.context.router.goBack();
        // browserHistory.goBack();
        // route(-1);
        hashHistory.goBack();
      }

    都不行。

    react router current route

    preact router current route

    暂时放一放，因为目前github无法打开，很多帖子和preact-router源码没法看。

    等github能访问了，再弄。

    然后目前用代码：

    app.js

    @connect(reducer, bindActions(actions))
    export default class App extends Component {
      state = {
        curUrl : "/",
        prevUrl : "/"
      };
      constructor(props) {
        super(props);
        autoBind(this);
      }
      handleRoute = e => {
        console.log(e);
        // console.log(e.router.activeClassName);
        console.log(e.router);
        // console.log(e.router.title);
        const currentUrl = e.url;
        // const currentUrl = "/uapp" + e.url;
        // console.log(this.currentUrl);
        console.log(currentUrl);
        const previousUrl = e.previous;
        console.log(previousUrl);
        this.setState({
          curUrl : currentUrl,
          prevUrl : previousUrl
        });
        console.log(this.state.curUrl);
        window.scrollTo(0, 0);
      };
      render() {
        const prop = this.props;
        return (
          <div id="app">
            <Loading show={prop.globalLoadingShown}/>
            {/*<Header title={this.state.currentTitle}/>*/}
            <Header curUrl={this.state.curUrl} prevUrl={this.state.prevUrl}/>

    header/index.js

    export default class Header extends Component {
      state = {
        curUrl : "",
        prevUrl : "1"
      }
      constructor(props) {
        super(props);
        // this.state.curUrl = this.props.curUrl;
        // this.state.prevUrl = this.props.prevUrl;
        console.log(`Header constructor: this.state.curUrl=${this.state.curUrl}, this.state.prevUrl=${this.state.prevUrl}, this.props.curUrl=${this.props.curUrl}, this.props.prevUrl=${this.props.prevUrl}`);
      }
      componentWillReceiveProps(nextProps) {
        this.setState({
          curUrl: nextProps.curUrl,
          prevUrl: nextProps.prevUrl
        });
        // this.forceUpdate();
      }
      render() {
        const pageType = this.parsePageType(this.state.curUrl);
        console.log(`Header render: this.state.curUrl=${this.state.curUrl}, this.state.prevUrl=${this.state.prevUrl}, this.props.curUrl=${this.props.curUrl}, this.props.prevUrl=${this.props.prevUrl}`);
        return (
          <header class={style.header_div}>
            <div class={style.header_con}>
              { this.showLeftIcon(pageType, this.state.prevUrl) }
              <div class={style.top_tit}>{pageType.title}</div>
              { this.showRightIcon(pageType) }
            </div>
          </header>
        );
      }
      showLeftIcon(curPageType, prevUrl){
        console.log(`showLeftIcon: prevUrl=${prevUrl}`);
        if (curPageType.left.icon === HEADER_ICON.NONE) {
          return null;
        } else if (curPageType.left.icon === HEADER_ICON.BACK) {
          return (
              <Link href={prevUrl}>
                <span/>
              </Link>
          );
        } else if (curPageType.left.icon === HEADER_ICON.SWITCH_COW_FARM) {
          return (
              <Link href={curPageType.left.link} class={style.home_qc} >
                切换牛场
              </Link>
          );
        }
        return null;
      }

    虽然实现了基本的，通过prevUrl，实现返回上一页，但是会出现嵌套死循环：

    点击子页面，比如 处理 或者右上角的加号，进入子页面的子页面

    但是此时点击返回，可以返回上一页：

    但是再点击 返回，还是回到之前的子页面了（而非期望的主页面）

    所以，还是没有真正解决问题。

    -》

    如果给每个页面，都强制指定一个前一页，则显得很麻烦。

    -》希望还是可以通过history back类似的逻辑，即页面调用stack栈，智能的实现页面跳转。

    所以还是：

    等github可以访问后，再去研究

    preact-router是否有history  back之类的功能

    preact-router history back

    Full hash-routing using preact-router · Issue #153 · developit/preact-router

    Route Transitions · Issue #29 · developit/preact-router

    preact-router history

    javascript – How to use React Router with Preact – Stack Overflow

    preact-router go back

    reactjs – Using goBack function from react-router-redux – Stack Overflow

    然后用了back的代码，结果点击返回按钮时出错：

    【间接解决】Preact-Router调用传递过去的history的back时出错：Uncaught TypeError Illegal invocation

    【总结】

    Preact-router是支持history.back()去返回上一页的，但是只能在父页面中使用，即只能在Router所在的页面使用。

    此处不能直接把history作为参数（比如叫routerHistory）传递给子页面，否则子页面中直接调用routerHistory.back是行不通的，会出错：Uncaught TypeError: Illegal invocation

    解决办法是：

    利用子页面调用父页面的函数，即可间接实现此效果：

    把父页面的history.back()单独弄成函数，传递给子页面，然后子页面即可随时调用此函数，实现返回前一页了。

    具体代码是：

    父页面app.js

    import { Router } from ‘preact-router’;
    import { browserHistory } from ‘preact-router’;
    import Header from ‘../components/header’;
    @connect(reducer, bindActions(actions))
    export default class App extends Component {
      state = {
        curUrl : "/",
        prevUrl : "/",
        routerHistory : null
      };
      constructor(props) {
        super(props);
        autoBind(this);
      }
      handleRoute = e => {
        console.log("handleRoute:");
        console.log(e);
        // console.log(e.router.activeClassName);
        console.log(e.router);
        // console.log(e.router.title);
        const currentUrl = e.url;
        // const currentUrl = "/uapp" + e.url;
        // console.log(this.currentUrl);
        console.log(currentUrl);
        // console.log(browserHistory);
        console.log(`history.location=${history.location}`);
        console.log("now do history.back()");
        // history.back();
        // console.log(`this.props.history=${this.props.history}`);
        // console.log(`this.state.history=${this.state.history}`);
        const previousUrl = e.previous;
        console.log(previousUrl);
        this.setState({
          curUrl : currentUrl,
          prevUrl : previousUrl,
          routerHistory : history
        });
        console.log(this.state.curUrl);
        window.scrollTo(0, 0);
      };
      goBackFunc(){
        console.log(`goBackFunc: history=${history}`);
        console.log(history);
        console.log(history.back);
        console.log("+++++ now do history.back()");
        history.back();
      }
      render() {
        const prop = this.props;
        return (
          …
           <Header curUrl={this.state.curUrl} prevUrl={this.state.prevUrl} routerHistory={this.state.routerHistory} goBackFunc={this.goBackFunc}/>
            <div class="container">
              <Router onChange={this.handleRoute} history={browserHistory}>
              {/*<Router onChange={this.handleRoute}>*/}
                <Main path="/" />
                <Profile path="/profile" />

    子页面Header/index.js

    export default class Header extends Component {
      state = {
        curUrl : "",
        prevUrl : "1",
        routerHistory : null
      }
      constructor(props) {
        super(props);
        // this.state.curUrl = this.props.curUrl;
        // this.state.prevUrl = this.props.prevUrl;
        console.log(`Header constructor: this.state.curUrl=${this.state.curUrl}, this.state.prevUrl=${this.state.prevUrl}, this.props.curUrl=${this.props.curUrl}, this.props.prevUrl=${this.props.prevUrl}`);
      }
      componentWillReceiveProps(nextProps) {
        this.setState({
          curUrl: nextProps.curUrl,
          prevUrl: nextProps.prevUrl,
          routerHistory : nextProps.routerHistory
        });
        // this.forceUpdate();
        // console.log(`Header componentWillReceiveProps: this.state.routerHistory=${this.state.routerHistory}, history=${history}, route=${route}, getCurrentUrl=${getCurrentUrl}`);
        console.log(`Header componentWillReceiveProps: this.state.routerHistory=${this.state.routerHistory}`);
      }
      render() {
        const pageType = this.parsePageType(this.state.curUrl);
        console.log(`Header render: this.state.curUrl=${this.state.curUrl}, this.state.prevUrl=${this.state.prevUrl}, this.props.curUrl=${this.props.curUrl}, this.props.prevUrl=${this.props.prevUrl}`);
        return (
          <header class={style.header_div}>
            <div class={style.header_con}>
              { this.showLeftIcon(pageType, this.props.goBackFunc) }
              {/*<a onClick={this.state.routerHistory.back}>*/}
              {/*<a onClick={this.state.routerHistory !== null ? this.state.routerHistory.back : ()=>{}}>*/}
              {/*<a onClick={this.props.goBackFunc}>
                <span/>
              </a>*/}
              <div class={style.top_tit}>{pageType.title}</div>
              { this.showRightIcon(pageType) }
            </div>
          </header>
        );
      }
              // <a onClick={this.goBackPage}>
              // <a onClick={route(prevUrl)}>
              //   <span/>
              // </a>
              // <Link href={prevUrl}>
              //   <span/>
              // </Link>
      // showLeftIcon(curPageType, prevUrl){
      //   console.log(`showLeftIcon: prevUrl=${prevUrl}`);
      // showLeftIcon(curPageType, curState){
      showLeftIcon(curPageType, goBackFunc){
        console.log(`showLeftIcon: goBackFunc=${goBackFunc}`);
        // console.log(`showLeftIcon: curState=${curState}`);
        // console.log(`showLeftIcon: curState.routerHistory=${curState.routerHistory}`);
        // console.log(curState.routerHistory);
        // if (curState.routerHistory !== null) {
        //   console.log(curState.routerHistory.back);
        //   const backFunction = curState.routerHistory.back;
        //   console.log(backFunction);
        // }
        if (curPageType.left.icon === HEADER_ICON.NONE) {
          return null;
        } else if (curPageType.left.icon === HEADER_ICON.BACK) {
          return (
              // <a onClick={backFunction}>
              // <a onClick={curState.routerHistory.back}>
              <a onClick={goBackFunc}>
                <span/>
              </a>
          );
        } else if (curPageType.left.icon === HEADER_ICON.SWITCH_COW_FARM) {
          return (
              <Link href={curPageType.left.link} class={style.home_qc} >
                切换牛场
              </Link>
          );
        }
        return null;
      }

    效果是：

    （1）比如最开始在首页

    （2）点击了进入配种子页面

    （3）点击处理

    （4）点击返回之前页面

    （5）点击加号去新增

    （6）再点击返回

    （7）此时，重点来了：点击返回就不会出现页面在之前的 处理和新增页面死循环的情况了，就可以正常返回首页了：

    转载请注明：在路上 » 【已解决】Preact-Router中如何通过路由实现返回上一页

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