javascript - Vanilla javascript轮播不滑动

Question

我有一个带有主要 div 的简单旋转木马。在主 div 中有一个宽度为 6000px 的 ul，每当我单击向右或向左箭头时，它就会滑动。

我将事件监听器附加到两个箭头，所以当我单击左箭头时，我将 300px 添加到该 ul(slider) 的当前 marginLeft 和右箭头的 marginRight 300px。

问题 1:当我单击向左箭头时，ul( slider )移动但只有 1 次当我单击第二次时它不会移动，即使我将 300px 添加到 marginLeft 而不是仅添加 300px 这是我看到的一个常见错误.

问题 2:当我单击右箭头时，它根本不会滑动 ul(slider)。

代码笔:https://codepen.io/anon/pen/bXBaYW?editors=0110

const carousel = document.getElementById('carousel');
const leftArrow = carousel.querySelector('.carousel-left-arrow');
const rightArrow = carousel.querySelector('.carousel-right-arrow');
const slides = carousel.querySelector('.slides');

function scrollLeft() {
    slides.style.marginLeft += '300px';
    console.log(slides.style.marginLeft);
}

function scrollRight() {
    slides.style.marginLeft -= '300px';
    console.log(slides.style.marginLeft);
}

leftArrow.addEventListener('click' , scrollLeft);
rightArrow.addEventListener('click' , scrollRight);

Answer 1

首先你应该这样增加:

 let marginLeft = 0; /* first define this as global */
 marginLeft += 300;
 slides.style.marginLeft = marginLeft + "px";

因为，"300px"+ "300px"= "300px300px" 你这样做的方式是错误的。

而且您无法获得像 element.style.marginLeft 这样的样式。

应该使用getComputedStyle(element).property

这是可行的。

const carousel = document.getElementById('carousel');
const leftArrow = carousel.querySelector('.carousel-left-arrow');
const rightArrow = carousel.querySelector('.carousel-right-arrow');
const slides = carousel.querySelector('.slides');

let marginLeft = 0;

function scrollLeft() {
  marginLeft += 300;
  slides.style.marginLeft = marginLeft + "px";
  console.log(getComputedStyle(slides).marginLeft);
}

function scrollRight() {
  marginLeft -= 300;
  slides.style.marginLeft = marginLeft + "px";
  console.log(getComputedStyle(slides).marginLeft);
}

leftArrow.addEventListener('click', scrollLeft);
rightArrow.addEventListener('click', scrollRight);

#carousel {
  width: 90%;
  margin: 0 auto;
  margin-top: 20px;
  overflow: hidden;
  position: relative;
}

#carousel .arrow {
  position: absolute;
  top: 32%;
  background-color: rgba(255, 255, 255, 0.7);
  border-radius: 0%;
  cursor: pointer;
  width: 20px;
}

#carousel .arrow img {
  margin-top: 10px;
  max-width: 100%;
}

#carousel .carousel-left-arrow {
  width: 25px;
  left: 0;
  margin-left: 5px;
}

#carousel .carousel-right-arrow {
  right: 0;
  width: 25px;
}

#carousel .slides {
  width: 6000px;
  overflow: hidden;
  list-style: none;
  padding: 0;
  transition: 0.2s;
  margin-left: 0;
  margin-right: 0
}

#carousel .slide {
  float: left;
  margin: 0 5px;
  text-decoration: none;
  transform: 0.2s;
  color: whitesmoke;
}

#carousel .slides img {
  width: 300px
}

<div id="carousel">
  <span class="carousel-left-arrow arrow"><</span>
  <ul class="slides">
    <a href='#' class="slide">
      <img src="https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500">
    </a>
    <a href='#' class="slide">
      <img src="https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500">
    </a>
    <a href='#' class="slide">
      <img src="https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500">
    </a>
    <a href='#' class="slide">
      <img src="https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500">
    </a>
    <a href='#' class="slide">
      <img src="https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500">
    </a>
    <a href='#' class="slide">
      <img src="https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500">
    </a>
  </ul>
  <span class="carousel-right-arrow arrow">></span>
</div>