javascript - 当用户使用javascript按下keybaord箭头键时如何更改图像

Question

所以我有这个画廊。当用户在模式弹出后按下箭头键时，我需要更改图像。左箭头键改变图像在左和右箭头键为右。我对javascript很陌生，所以如果你能帮助我，那就太好了。请查看完整页面的代码片段。

function openModal() {
            document.getElementById("myModal").style.display = "block";
          }
          function closeModal() {
            document.getElementById("myModal").style.display = "none";
          }
          var slideIndex = 1;
          showSlides(slideIndex);
          function plusSlides(n) {
            showSlides(slideIndex += n);
          }
          function currentSlide(n) {
            showSlides(slideIndex = n);
          }
          function showSlides(n) {
            var i;
            var slides = document.getElementsByClassName("mySlides");
            var dots = document.getElementsByClassName("demo");
            if (n > slides.length) {
              slideIndex = 1
            }
            if (n < 1) {
              slideIndex = slides.length
            }
            for (i = 0; i < slides.length; i++) {
              slides[i].style.display = "none";
            }
            slides[slideIndex - 1].style.display = "block";
          }

    .modal {
      width: 58%;
      height: 100%;
      top: 0;
      position: fixed;
      display: none;
      background-color: rgba(22, 22, 22, 0.5);
      margin-left: 300px;
      max-width: 779px;
      min-width: 779px;
    }


    .modal-content {
      margin: auto;
      display: block;
      width: 80%;
      max-width: 700px;
    }

    .mySlides {
      display: none;
    }
   .mySlides {
      display: none;
    }

    .cursor {
      cursor: pointer;
    }

    .cursor {
      cursor: pointer;
    }

    .prev {
      cursor: pointer;
      position: relative;
      top: -149px;
      padding: 16px;
      margin-top: -50px;
      color: white;
      font-weight: bold;
      font-size: 20px;
      border-radius: 0 3px 3px 0;
      user-select: none;
      -webkit-user-select: none;
      left: -10%;
    }

    .next {
      cursor: pointer;
      position: relative;
      top: -149px;
      padding: 16px;
      margin-top: -50px;
      color: white;
      font-weight: bold;
      font-size: 20px;
      border-radius: 0 3px 3px 0;
      user-select: none;
      -webkit-user-select: none;
      left: 600px;
    }

 <div class="main-container">
    <div class="row">
      <div class="column">
        <p align="center"><img src="https://source.unsplash.com/collection/190727/300x200" width="250" height="164"
            onclick="openModal();currentSlide(1)" class="hover-shadow cursor"></p>
      </div>
      <div class="column">
        <p align="center"><img src="https://source.unsplash.com/collection/190727/300x210" width="250" height="164"
            onclick="openModal();currentSlide(2)" class="hover-shadow cursor"></p>
      </div>
      <div id="myModal" class="modal">
        <div class="modal-content">
          <span class="close cursor" onclick="closeModal()">&times;</span>
          <div class="mySlides">
            <img src="https://source.unsplash.com/collection/190727/300x200" style="width: 98%;
position: relative;
left: 10px;
top: 109px;">
          </div>
          <div class="mySlides">
            <img src="https://source.unsplash.com/collection/190727/300x210" style="width: 98%;
position: relative;
left: 10px;
top: 109px;">
          </div>
          <a class="prev" id="prev1" onclick="plusSlides(-1)">&#10094;</a>
          <a class="next" onclick="plusSlides(1)">&#10095;</a>
        </div>

标签： javascripthtmlcss

Answer 1

要检测箭头键按下，您可以添加 keydown 事件监听器并检查键码。左箭头键的键码是 37，右箭头键的键码是 39。

document.addEventListener('keydown', function(e) {
  if (e.keyCode === 37) {
    // Left arrow key is pressed
  } else if (e.keyCode === 39) {
    // Right arrow key is pressed
  }
});