Javascript 在浏览器中单击“处理后退/前进”按钮 如果用户单击浏览器中的“前进”按钮，我希望console.log（1） -1如果用户单击后退按钮 0如果用户重新加载页面

这是我到目前为止的代码，我无法实现得到-1，为什么我做错了

我的方法是在组件中的历史对象内部设置一个状态，并将其与历史对象的长度进行比较

async function handleBackForwardButton() {

    // If none, then zero
    const historyLength = Number(sessionStorage.getItem("historyLength"));
    let { state } = await window.history.state; 
    let position;
    if (state === null || state === undefined) {
      // New entry on the stack
      position = historyLength + 1;
      debugger;
      //  Stamp the entry with its own position in the stack
      window.history.replaceState(historyLength, /*no title*/ "");
      // (2) Keep track of the last position shown
      sessionStorage.setItem("historyLength", String(window.history.length));
      debugger;
      // (3) Discover the direction of travel by comparing the two
      const direction = Math.sign(position - historyLength);
      console.log("Forward should be (1) :" + direction);
      debugger;
      // forward should be (1)
    } else if (historyLength > state) {
      const direction = Math.sign(state - historyLength);
      console.log("Backward should be (-1) :" + direction);
      debugger;
      //One of backward (-1)
    } else if (historyLength === state) {
      const direction = Math.sign(state - historyLength);
      console.log("Reloading page should be (0) : " + direction);
      debugger;
      //Reloading page should be (0)
    }
  }

  window.addEventListener("pageshow", handleBackForwardButton);
  window.addEventListener("popstate", handleBackForwardButton); 

这可能有助于：