React Router——在listen()中区分goBack()和goForward()

Question

问题

使用 React Router v4，如何区分goBack()和goForward()调用listen()方法？

据我所知，location和action参数没有提供足够的信息来区分。该action参数是POP两个前进和后退。

history.listen((location, action) => {
  // action = 'POP' when goBack() and goForward() are called.
}

我正在使用 历史节点模块。

目的

我有一个面包屑组件，其项目保持在状态。当用户返回时，我需要弹出最后一个面包屑。

Answer 1

您可以key从location数组中的对象中收集所有值，并使用它来确定键是按顺序出现在前一个之前还是之后，并使用它来区分 agoBack和goForward。

例子

const keys = [];
let previousKey;

history.listen((location, action) => {
  const { key } = location;

  // If there is no key, it was a goBack.
  if (key === undefined) {
    console.log('goBack')
    return;
  }

  // If it's an entirely new key, it was a goForward.
  // If it was neither of the above, you can compare the index 
  // of `key` to the previous key in your keys array.  
  if (!keys.includes(key)) {
    keys.push(key);
    console.log('goForward');
  } else if (keys.indexOf(key) < keys.indexOf(previousKey)) {
    console.log('goBack');
  } else {
    console.log('goForward');
  }

  previousKey = key;
});

history.push("/test");
history.push("/test/again");
setTimeout(() => history.goBack(), 1000);
setTimeout(() => history.goBack(), 2000);
setTimeout(() => history.goForward(), 3000);