Почему этот javascript работает только в теге script, а не в файле .js?

Я погуглил несколько хороших слайдеров изображений и наткнулся на этот. Когда я помещаю javascript в тег script в html, он работает нормально, но когда я пытаюсь поместить его в файл .js, связанный с html, он перестает работать, и я не могу понять, почему. Когда я смотрю на вывод консоли, он говорит, что не может прочитать «addEventListener» в строке 10. Заранее спасибо :)

* {
  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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          voluptates inventore. In corrupti hic eos, incidunt iusto dignissimos
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        </p>
      </div>
      <footer id = "footer">
        <p id = "footer-text">Lorem ipsum dolor sit amet consectetur.</p>
      </footer>
    </main>
  </body>
</html>

Включите HTML-код, если он находится в теге скрипта.

— 14.02.2023 18:09

When I look at the console output, it says it can't read the "addEventListener" at line 10. Что именно там написано? Покажи свой HTML.

— 14.02.2023 18:09

Я не удивлюсь, если скрипт запустится до того, как будет отображен HTML.

— 14.02.2023 18:10

javascript html css

14.02.2023 18:08

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Перейти к ответу Данный вопрос помечен как решенный

Ответы 1

Ответ принят как подходящий

Да, что сказал @evolutionxbox. Если у вас есть JS, включенный в заголовок или любое место выше, где вы определили nextBtn в HTML, или любые другие элементы, которые вы планируете использовать, то эти элементы будут нулевыми при выполнении скрипта.

Вы должны убедиться, что ваш сценарий запускается после загрузки документа, поместив вышеуказанное в функцию и запустив ее, присоединив указанную функцию к событию загрузки окна.

Включение JS должно выглядеть примерно так:

function yourScript(){
/* Your script goes here */
}

window.addEventListener("load",yourScript);

Вы также можете использовать

window.addEventListener("DOMContentLoaded",yourscript);

Если вы хотите запустить скрипт после анализа DOM, но до загрузки изображений и другого стороннего контента. Это, вероятно, хорошо для вашего сценария.

Популярный способ сделать это в наши дни — просто поместить тег сценария перед закрывающим тегом </body>. или используйте атрибут defer.

— 14.02.2023 18:17

14.02.2023 18:15