• • 此问题在此处已有答案**：

Why does jQuery or a DOM method such as getElementById not find the element?（6个答案）
2天前关闭。
我在谷歌上搜索了一些不错的图片滑块，偶然发现了这个。当我把javascript放在html的script标签中时，它工作得很好，但是当我试图把它放在链接到html的. js文件中时，它就停止工作了，我不知道为什么。当我查看控制台输出时，它说它不能读取第10行的"addEventListener"。谢谢你了：）

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  overflow: hidden;
}

body {
  background-color: #262626;

  font-family: "Roboto Slab", serif;

  position: relative;
  overflow-x: hidden;
}

main {
  width: 100vw;
  height: 100vh;
}

#backdrop {
  width: 90%;
  height: 100%;

  margin: 0 auto;
  margin-top: 1rem;
  border-radius: 1rem 1rem 0 0;

  background-color: #727365;
}

#home-link {
  color: #f2f2e4;
  text-decoration: none;
  font-size: 1.7rem;
  font-family: "Space Mono", monospace;
  font-weight: 400;

  position: absolute;
  top: 1.95rem;
  left: 2.6rem;
}

/* Hamburger menu */
#menu a {
  text-decoration: none;
  color: #262626;
}

#menu a:hover {
  color: #0c0c0c;
}

#menu-toggle {
  display: block;

  position: absolute;
  top: 2.5rem;
  right: 3rem;

  z-index: 1;
}

#menu-checkbox {
  display: block;

  width: 40px;
  height: 32px;

  position: absolute;
  top: -7px;
  left: -5px;

  cursor: pointer;

  opacity: 0;
  z-index: 2;
}

#menu-toggle span {
  display: block;

  width: 33px;
  height: 4px;

  margin-bottom: 5px;
  position: relative;

  background: #f2f2e4;
  border-radius: 3px;

  z-index: 1;

  transform-origin: 4px 0px;
  transition: transform 0.5s cubic-bezier(0.77, 0.2, 0.05, 1),
    opacity 0.55s ease;
}

#menu-toggle span:first-child {
  transform-origin: 0% 0%;
}

#menu-toggle span:nth-last-child(2) {
  transform-origin: 0% 100%;
}

#menu-checkbox:checked ~ span {
  opacity: 1;
  transform: rotate(45deg) translate(-2px, -1px);
  background: #3f403b;
}

#menu-checkbox:checked ~ span:nth-last-child(3) {
  opacity: 0;
  transform: rotate(0deg) scale(0.2, 0.2);
}

#menu-checkbox:checked ~ span:nth-last-child(2) {
  opacity: 1;
  transform: rotate(-45deg) translate(0, -1px);
}

#menu {
  width: 60vw;
  height: 70vh;

  position: absolute;
  right: -100px;

  margin: -100px 0 0 0;
  padding: 50px;
  padding-top: 125px;
  border-radius: 1rem;

  background-color: #bfbfae;
  list-style: none;

  transform-origin: 0% 0%;
  transform: translate(100%, 0);
  transition: transform 0.5s cubic-bezier(0.77, 0.2, 0.05, 1);
}

#menu li {
  padding: 10px 0;
  font-size: 22px;
}

#menu-checkbox:checked ~ ul {
  transform: none;
  opacity: 1;
}

/* footer */
#footer {
  position: absolute;
  top: 100vh;
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 13px;
}

::-webkit-scrollbar-thumb {
  border-radius: 100px;
  border: 3px solid transparent;
  background-clip: content-box;
  background-color: rgb(88, 88, 88);
}

::-webkit-scrollbar-thumb:hover {
  background-color: rgb(109, 109, 109);
}

/* Media queries */
@media only screen and (min-width: 600px) {
}

@media only screen and (min-width: 769px) {
  #backdrop {
    margin-top: 2vh;
    width: 98%;
    height: 96.5%;
    border-radius: 1rem;
  }

  #menu-checkbox {
    display: none;
  }

  #menu-toggle span {
    display: none;
  }

  #menu {
    -webkit-transition: none !important;
    -moz-transition: none !important;
    -o-transition: none !important;
    transition: none !important;
    transform: none !important;

    background-color: rgba(160, 160, 160, 0.568);
    backdrop-filter: blur(15px);

    padding: 0 1rem 0 1rem;
    border-radius: 2rem;
    font-family: monospace;

    position: fixed;
    top: 102vh;
    right: 50%;
    translate: 50% 0;

    height: fit-content;
    width: 45vw;

    display: flex;
    justify-content: space-between;
  }

  #menu li {
    display: inline;
    font-size: 1.2rem;
  }

  #active {
    background-color: #f2f2e4;

    border-radius: 3rem;
  }

  .menu-links {
    padding: 8px 35px 8px 35px;
  }

  #home-link {
    display: flex;
    justify-content: center;
    position: static;

    padding-top: 0.5rem;
  }
}

.slider{
  position: relative;
  background: #000116;
  width: 800px;
  min-height: 500px;
  margin: 20px;
  overflow: hidden;
  border-radius: 10px;
}

.slider .slide{
  position: absolute;
  width: 100%;
  height: 100%;
  clip-path: circle(0% at 0 50%);
}

.slider .slide.active{
  clip-path: circle(150% at 0 50%);
  transition: 2s;
}

.slider .slide img{
  position: absolute;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.slider .slide .info{
  position: absolute;
  color: #222;
  background: rgba(255, 255, 255, 0.3);
  width: 75%;
  margin-top: 50px;
  margin-left: 50px;
  padding: 20px;
  border-radius: 5px;
  box-shadow: 0 5px 25px rgb(1 1 1 / 5%);
}

.slider .slide .info h2{
  font-size: 2em;
  font-weight: 800;
}

.slider .slide .info p{
  font-size: 1em;
  font-weight: 400;
}

.navigation{
  height: 500px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  opacity: 0;
  transition: opacity 0.5s ease;
}

.slider:hover .navigation{
  opacity: 1;
}

.prev-btn, .next-btn{
  z-index: 999;
  font-size: 2em;
  color: #222;
  background: rgba(255, 255, 255, 0.8);
  padding: 10px;
  cursor: pointer;
}

.prev-btn{
  border-top-right-radius: 3px;
  border-bottom-right-radius: 3px;
}

.next-btn{
  border-top-left-radius: 3px;
  border-bottom-left-radius: 3px;
}

.navigation-visibility{
  z-index: 999;
  display: flex;
  justify-content: center;
}

.navigation-visibility .slide-icon{
  z-index: 999;
  background: rgba(255, 255, 255, 0.5);
  width: 20px;
  height: 10px;
  transform: translateY(-50px);
  margin: 0 6px;
  border-radius: 2px;
  box-shadow: 0 5px 25px rgb(1 1 1 / 20%);
}

.navigation-visibility .slide-icon.active{
  background: #4285F4;
}

@media (max-width: 900px){
  .slider{
    width: 100%;
  }

  .slider .slide .info{
    position: relative;
    width: 80%;
    margin-left: auto;
    margin-right: auto;
  }
}

@media (max-width: 500px){
  .slider .slide .info h2{
    font-size: 1.8em;
    line-height: 40px;
  }

  .slider .slide .info p{
    font-size: 0.9em;
  }
}

/*.mySlides {
  display: none;
}

/* Slideshow container 
.slideshow-container {
  width: 100%;
  height: 100%;
  max-height: 100vh;
  margin: auto;
}
/* The dots/bullets/indicators 
.dot {
  height: 15px;
  width: 15px;
  margin: 0 2px;
  background-color: #bbb;
  border-radius: 50%;
  display: inline-block;
  transition: background-color 0.6s ease;
}

.active {
  background-color: #717171;
}

/* On smaller screens, decrease text size 
@media only screen and (max-width: 300px) {
  .prev,
  .next,
  .text {
    font-size: 11px;
  }
}

/* Next & previous buttons 
.prev,
.next {
  cursor: pointer;
  position: absolute;
  top: 50%;
  width: auto;
  padding: 16px;
  margin-top: -22px;
  color: white;
  font-weight: bold;
  font-size: 18px;
  transition: 0.6s ease;
  border-radius: 0 3px 3px 0;
  user-select: none;
}

/* Position the "next button" to the right 
.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}

/* On hover, add a black background color with a little bit see-through 
.prev:hover,
.next:hover {
  background-color: rgba(0, 0, 0, 0.8);
}

<!DOCTYPE html>
<html lang="sv">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <title>Överdäckningen | Startsida</title>
    <link rel="stylesheet" href="css/style.css" />
    <script type="text/javascript" src="script/js.js"></script>
    <link
      href="https://fonts.googleapis.com/css2?family=Roboto+Slab:wght@200;300;400&display=swap"
      rel="stylesheet"
    />
    <link
      href="https://fonts.googleapis.com/css2?family=Space+Mono&display=swap"
      rel="stylesheet"
    />
    <link
      rel="stylesheet"
      href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.3/css/all.min.css"
    />
  </head>
  <!--
    Göra så loggan försvinner när man scrollar ner och kommer tillbaka när man scrollar upp

    navbar responsiv, desktop

    mediaquery för ipad

    bilder, text

    göra så bildspelet passar in

    anpassa alla bilder för skärmstorlek, picture element

    (karta kanske?)

    lägga rätt fonter på rubriker och text
  -->
  <body>
    <main>
      <div id="backdrop">
        <div class="slider">
          <div class="slide active">
            <img src="imgs/1.jpg" alt="" />
            <div class="info">
              <h2>Winter Mountains</h2>
              <p>
                Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do
                eiusmod tempor incididunt ut labore et dolore magna aliqua.
              </p>
            </div>
          </div>
          <div class="slide">
            <img src="imgs/2.jpg" alt="" />
            <div class="info">
              <h2>Tropical Desert</h2>
              <p>
                Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do
                eiusmod tempor incididunt ut labore et dolore magna aliqua.
              </p>
            </div>
          </div>
          <div class="slide">
            <img src="imgs/3.jpg" alt="" />
            <div class="info">
              <h2>Steaming Volcanoes</h2>
              <p>
                Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do
                eiusmod tempor incididunt ut labore et dolore magna aliqua.
              </p>
            </div>
          </div>
          <div class="slide">
            <img src="imgs/4.jpg" alt="" />
            <div class="info">
              <h2>Mountain River</h2>
              <p>
                Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do
                eiusmod tempor incididunt ut labore et dolore magna aliqua.
              </p>
            </div>
          </div>
          <div class="slide">
            <img src="imgs/5.jpg" alt="" />
            <div class="info">
              <h2>Egypt Pyramids</h2>
              <p>
                Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do
                eiusmod tempor incididunt ut labore et dolore magna aliqua.
              </p>
            </div>
          </div>
          <div class="navigation">
            <i class="fas fa-chevron-left prev-btn"></i>
            <i class="fas fa-chevron-right next-btn"></i>
          </div>
          <div class="navigation-visibility">
            <div class="slide-icon active"></div>
            <div class="slide-icon"></div>
            <div class="slide-icon"></div>
            <div class="slide-icon"></div>
            <div class="slide-icon"></div>
          </div>
        </div>
        <script type="text/javascript">
          const slider = document.querySelector(".slider");
          const nextBtn = document.querySelector(".next-btn");
          const prevBtn = document.querySelector(".prev-btn");
          const slides = document.querySelectorAll(".slide");
          const slideIcons = document.querySelectorAll(".slide-icon");
          const numberOfSlides = slides.length;
          var slideNumber = 0;

          //image slider next button
          nextBtn.addEventListener("click", () => {
            slides.forEach((slide) => {
              slide.classList.remove("active");
            });
            slideIcons.forEach((slideIcon) => {
              slideIcon.classList.remove("active");
            });

            slideNumber++;

            if (slideNumber > numberOfSlides - 1) {
              slideNumber = 0;
            }

            slides[slideNumber].classList.add("active");
            slideIcons[slideNumber].classList.add("active");
          });

          //image slider previous button
          prevBtn.addEventListener("click", () => {
            slides.forEach((slide) => {
              slide.classList.remove("active");
            });
            slideIcons.forEach((slideIcon) => {
              slideIcon.classList.remove("active");
            });

            slideNumber--;

            if (slideNumber < 0) {
              slideNumber = numberOfSlides - 1;
            }

            slides[slideNumber].classList.add("active");
            slideIcons[slideNumber].classList.add("active");
          });

          //image slider autoplay
          var playSlider;

          var repeater = () => {
            playSlider = setInterval(function () {
              slides.forEach((slide) => {
                slide.classList.remove("active");
              });
              slideIcons.forEach((slideIcon) => {
                slideIcon.classList.remove("active");
              });

              slideNumber++;

              if (slideNumber > numberOfSlides - 1) {
                slideNumber = 0;
              }

              slides[slideNumber].classList.add("active");
              slideIcons[slideNumber].classList.add("active");
            }, 4000);
          };
          repeater();

          //stop the image slider autoplay on mouseover
          slider.addEventListener("mouseover", () => {
            clearInterval(playSlider);
          });

          //start the image slider autoplay again on mouseout
          slider.addEventListener("mouseout", () => {
            repeater();
          });
        </script>
        <header id="wrapper">
          <nav>
            <a href="index.html" id="home-link">ÖVERDÄCKNINGEN</a>
            <div id="menu-toggle">
              <input id="menu-checkbox" type="checkbox" />
              <span class="hamburger-span"></span>
              <span class="hamburger-span"></span>
              <span class="hamburger-span"></span>
              <ul id="menu">
                <li><a class="menu-links" id="active" href="#">Länk 1</a></li>
                <li><a class="menu-links" href="html/link2.html">Länk 2</a></li>
                <li><a class="menu-links" href="html/link3.html">Länk 3</a></li>
                <li><a class="menu-links" href="html/link4.html">Länk 4</a></li>
              </ul>
            </div>
          </nav>
        </header>
      </div>
      <div>
        <p>
          Lorem ipsum dolor sit amet, consectetur adipisicing elit. Porro amet
          dolores nisi delectus ad inventore laboriosam alias, architecto eos
          sunt quod eum maiores provident aspernatur debitis ratione minus
          quaerat cumque veniam. Delectus commodi odit molestiae excepturi.
          Doloremque rem tempora quod est veritatis earum accusamus vel fugiat
          numquam reprehenderit ad labore repudiandae recusandae neque
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          et at aut iste obcaecati nisi, vitae repellat placeat quasi iusto.
          Rerum vero eos earum nobis in inventore quos aliquid id, assumenda
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          Perferendis, id odit. Laudantium, culpa. Iure placeat deserunt
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          eum at distinctio dicta aut molestias sunt, totam ab eligendi
          possimus. Ipsa, dolorem numquam sint doloribus reprehenderit
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        </p>
      </div>
      <footer id="footer">
        <p id="footer-text">Lorem ipsum dolor sit amet consectetur.</p>
      </footer>
    </main>
  </body>
</html>