javascript - Javascript ES6 中调整窗口大小问题

Question

在我之前的post中我请求帮助修复某些部分，同时在没有框架的 Vanilla ES6 中滚动。

简单的 HTML 结构:

<header class="forewords"><h1>Lorem some</h1>
</header>

<div class="wrapper">
 <section class="project" id="item1">this is section 1</section>
 <section class="project" id="item2">this is section 2</section>
 <section class="project" id="item3">this is section 3</section>
</div>

<footer class="endings"><h1>Lorem something.</h1>
</footer>

这是完成这项工作的核心函数:

function pinElement() {

  // Reset all styles 
  projects.forEach((project) => {
    document.body.style.paddingTop = 0;
    project.classList.remove('fixed');
  });

  // Get the index of the project that is closest to top
  const valueClosestToScrollY = Math.max.apply(Math, projectsOffsetTop.filter((offsetTop) => offsetTop <= window.scrollY));
  const idx = projectsOffsetTop.indexOf(valueClosestToScrollY);


  // Otherwise, we set the appropriate styles and classes
  if (window.scrollY >= projectsOffsetTop[idx]) {
    document.body.style.paddingTop = `${projectsHeight[idx]}px`;
    projects[idx].classList.add('fixed');
  } 

};

window.addEventListener('scroll', pinElement);

现在我在调整窗口大小时遇到​​问题。

我添加了一个事件监听器，以便在有人调整窗口大小时更新元素的偏移和高度值。

function updateProjectsOffsetTop() {
  projectsOffsetTop = projects.map(project => project.offsetTop);
  projectsHeight = projects.map(project => project.offsetHeight);
};

window.addEventListener('resize', updateProjectsOffsetTop);

如果我在开始滚动之前调整窗口大小，则效果很好。但如果我在开始滚动后调整窗口大小，一切都会崩溃。

我无法找到实时更新值并将其传递给滚动函数的方法。如果可能的话，我想用 Vanilla ES6 来解决这个代码，因为我正在尝试从该规范开始学习 Javascript。

我知道也许这是一个简单的问题，但我是来学习的:)

提前致谢，并找到附件中完整的 JS Fiddle。

const projects = Array.from(document.querySelectorAll('.project'));
    let projectsOffsetTop = projects.map(project => project.offsetTop);
    let projectsHeight = projects.map(project => project.offsetHeight);

    function updateProjectsOffsetTop() {
      projectsOffsetTop = projects.map(project => project.offsetTop);
      projectsHeight = projects.map(project => project.offsetHeight);
    };


    function pinElement() {

      // Reset all styles 
      projects.forEach((project) => {
        document.body.style.paddingTop = 0;
        project.classList.remove('fixed');
      });

      // Get the index of the project that is closest to top
      const valueClosestToScrollY = Math.max.apply(Math, projectsOffsetTop.filter((offsetTop) => offsetTop <= window.scrollY));
      const idx = projectsOffsetTop.indexOf(valueClosestToScrollY);


      // Otherwise, we set the appropriate styles and classes
      if (window.scrollY >= projectsOffsetTop[idx]) {
        document.body.style.paddingTop = `${projectsHeight[idx]}px`;
        projects[idx].classList.add('fixed');
      } 

    };

    window.addEventListener('resize', updateProjectsOffsetTop);
    window.addEventListener('scroll', pinElement);

html {
      box-sizing: border-box;
    }

    *, *::before, *::after {
      box-sizing: inherit;
      margin: 0;
      padding: 0;
    }

    header, footer {
      width: 100%;
      padding: 10%;
      background-color: grey;
      position: relative;
    }

    .project {
      width: 100%;
      height: 100vh;
      position: relative;
      display: flex;
      justify-content: center;
      align-items: center;
      top: 0;
    }

    #item1 {background-color: yellow;}
    #item2 {background-color: blue;}
    #item3 {background-color: red;}


    .fixed {
      position: fixed;
    }

<header class="forewords"><h1>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Harum soluta ipsam quaerat cupiditate neque, necessitatibus amet nihil perferendis sunt minus! Exercitationem nulla inventore, aut beatae magnam, totam et minus hic.</h1>
  </header>

  <div class="wrapper">
    <section class="project" id="item1">this is section 1</section>
    <section class="project" id="item2">this is section 2</section>
    <section class="project" id="item3">this is section 3</section>
  </div>

  <footer class="endings"><h1>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Repudiandae vel, perferendis ullam totam recusandae sed repellendus cum! Molestiae, aut ut sequi eos quidem nam quo est, ad tempora inventore odit.</h1>
  </footer>

Answer 1

当您运行updateProjectsOffsetTop时并有一个 <section>已设置为position: fixed该固定元素的 offsetTop 始终为 0。

当您调整大小(滚动后)并获取新的偏移量时，任何元素的偏移量当前为 fixed将为零。因此破坏了你的逻辑 valueClosestToScrollY稍后。

您只需清除 fixed 即可解决此问题元素，设置偏移量，然后重新运行 pinElement()如下；

function updateProjectsOffsetTop() {
  projects.forEach((project) => {
    document.body.style.paddingTop = 0;
    project.classList.remove('fixed');
  });
  projectsOffsetTop = projects.map(project => project.offsetTop);
  projectsHeight = projects.map(project => project.offsetHeight);
  pinElement();
};

这可能不完全是您想要实现的方式，但这就是问题所在。

const projects = Array.from(document.querySelectorAll('.project'));
    let projectsOffsetTop = projects.map(project => project.offsetTop);
    let projectsHeight = projects.map(project => project.offsetHeight);

    function updateProjectsOffsetTop() {
      projects.forEach((project) => {
        document.body.style.paddingTop = 0;
        project.classList.remove('fixed');
      });
      projectsOffsetTop = projects.map(project => project.offsetTop);
      projectsHeight = projects.map(project => project.offsetHeight);
      pinElement();
    };


    function pinElement() {

      // Reset all styles 
      projects.forEach((project) => {
        document.body.style.paddingTop = 0;
        project.classList.remove('fixed');
      });

      // Get the index of the project that is closest to top
      const valueClosestToScrollY = Math.max.apply(Math, projectsOffsetTop.filter((offsetTop) => offsetTop <= window.scrollY));
      const idx = projectsOffsetTop.indexOf(valueClosestToScrollY);


      // Otherwise, we set the appropriate styles and classes
      if (window.scrollY >= projectsOffsetTop[idx]) {
        document.body.style.paddingTop = `${projectsHeight[idx]}px`;
        projects[idx].classList.add('fixed');
      } 

    };

    window.addEventListener('resize', updateProjectsOffsetTop);
    window.addEventListener('scroll', pinElement);

html {
      box-sizing: border-box;
    }

    *, *::before, *::after {
      box-sizing: inherit;
      margin: 0;
      padding: 0;
    }

    header, footer {
      width: 100%;
      padding: 10%;
      background-color: grey;
      position: relative;
    }

    .project {
      width: 100%;
      height: 100vh;
      position: relative;
      display: flex;
      justify-content: center;
      align-items: center;
      top: 0;
    }

    #item1 {background-color: yellow;}
    #item2 {background-color: blue;}
    #item3 {background-color: red;}


    .fixed {
      position: fixed;
    }

<header class="forewords"><h1>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Harum soluta ipsam quaerat cupiditate neque, necessitatibus amet nihil perferendis sunt minus! Exercitationem nulla inventore, aut beatae magnam, totam et minus hic.</h1>
  </header>

  <div class="wrapper">
    <section class="project" id="item1">this is section 1</section>
    <section class="project" id="item2">this is section 2</section>
    <section class="project" id="item3">this is section 3</section>
  </div>

  <footer class="endings"><h1>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Repudiandae vel, perferendis ullam totam recusandae sed repellendus cum! Molestiae, aut ut sequi eos quidem nam quo est, ad tempora inventore odit.</h1>
  </footer>