javascript - 当 div ID 位于窗口顶部时有条件的 addEventListener

Question

我正在尝试使用 addEventListener当用户 scroll进入视野<div id="container"> .我是通过滚动高度来完成的，但我尝试 addEventListener什么时候<div>位于窗口顶部。

handleHeaderStuck = () => {
    if (this.innerContainer.scrollTop <= 500 && this.state.isStuck === true) {
        this.setState({isStuck: false});
    }
    else if (this.innerContainer.scrollTop >= 500 && this.state.isStuck !== true) {
        this.setState({isStuck: true});
    }
}

这将 setState滚动时 500px .

如何替换 500px 的条件当用户使用 id="container" 时设置作为窗口的顶部？同时替换 isStuck状态为 isStuckBottom当用户到达 div 的底部时。

完整代码为

constructor(props) {
    super(props)
    this.state = {
      isStuck: false,
    }
    this.handleHeaderStuck = this.handleHeaderStuck.bind(this)
  }

  innerContainer = null

  componentDidMount () {
    this.innerContainer.addEventListener("scroll", this.handleHeaderStuck);
  }

  componentWillUnmount () {
    this.innerContainer.removeEventListener("scroll", this.handleHeaderStuck);    
  }

  handleHeaderStuck = () => {
     if (this.innerContainer.scrollTop <= 500 && this.state.isStuck === true) {
        this.setState({isStuck: false});
     }
     else if (this.innerContainer.scrollTop >= 500 && this.state.isStuck !== true) {
        this.setState({isStuck: true});
     }
  }

Answer 1

  var atTop = false;
    var atBotton = false;
    document.addEventListener("scroll", e => {

      var elemInfo = document.getElementById("container").getClientRects()[0];
      if (parseInt(elemInfo.bottom) >= window.innerHeight) 
      {
      	if (!atBottom){
          console.log("I touche the bottom")
          document.getElementById("information").innerHTML = "mouse  reached the bottom";
          atBottom = true;
        }
        atTop = false;
      } else if (parseInt(elemInfo.top) <= 0) {
        if (!atTop) {
          console.log("Mouse at top")
          document.getElementById("information").innerHTML = "I touched the top";
          atTop = true;
        }
        atBottom = false;
      } else {
          console.log("I touched the nothing")
      }
    });

body {
      margin: 0px;
      padding: 0px;
      border: 0px;
    }

    .first, .bottom {
      width: 100%;
      height: 200px;
      background-color: Green;
    }

    #container {
      width: 100%;
      background-color: Yellow;
      margin: 0px;
      padding: 0px;
      border: 1 px solid black;
      height: 200px;
    }

    #infomation {
      font-size: 50px;
    }

    <div class="example">

    </div>
    <div id=container>
    <div id=information></div></div>
    <div class="bottom">

    </div>