Javascript：在没有 Jquery 或插件的情况下放大鼠标悬停

Question

几周来我到处都在寻找这个，但我就是找不到任何东西来告诉我我做错了什么或者如何继续。目标是创建一个类似于亚马逊在鼠标悬停时放大小图片产品的功能。

虽然我知道我需要两张图片，一张 "zoomed in" 尺寸，一张 "zoomed out" 尺寸，但我目前不知道如何进行。 我没有使用 Jquery- 我无法根据雇主的要求将它或任何插件安装到网站。我基本上是在要求更难的答案，对此我提前表示歉意。我必须从头开始做这件事。警告：我是一名编程学生。随你便吧。

我有 HTML 和 CSS 脚本，因为我们实际上没有 IDE 这里我在 codecademy 的项目部分做这个，否则我' d 必须完全现场编程。您可以找到我的代码 here，但我也会 post 下面的代码，因为 link 必然会更改代码，因为它使用程序保存。

注意：我原来有它，所以灰色框在相对中心跟随我的鼠标。它在移动时闪烁，但它正在工作。目前虽然决定不这样做，至少在我的工作电脑上是这样。我没有在我的个人电脑上测试过它。

编辑：代码在我的 Surface Pro 3 上运行，尽管它确实跟随鼠标离开图像（这是临时的，我随机抓取的东西）。我不确定为什么代码不能在我的工作计算机上运行，尽管这很可能是因为它是 Macintosh OSX 版本 10.6.8...

HTML代码:

<!DOCTYPE html>
<html>
<head>
    <link rel='stylesheet' href='style.css'/>
    <script src='script.js'></script>
</head>
<body>

<img id="imgZoom" onmousemove="zoomIn()" onmouseout="zoomOut()" src="http://ginger-mum.com/wp-content/uploads/2015/10/3633-1269758855-0da5042c33400a811a5d766be4579cb8.jpg">
<div id="overlay" onmousemove="zoomIn()"></div>
</body>
</html>

CSS代码:

#imgZoom {
    height: 300;
}

#overlay {
    visibility: hidden;
    position: absolute;
    left: 0px;
    top: 0px;
    width:20%;
    height:20%;
    padding: 25px;
    border: 5px solid gray;
    background-color: white;
    opacity:0.4;
    text-align:center;
    z-index: 1000;
}

Javascript代码:

function zoomIn()
{
    var element = document.getElementById("overlay");
    element.style.visibility = "visible";

    var x = event.clientX;     // Get the horizontal coordinate
    var y = event.clientY;     // Get the vertical coordinate

    element.style.top = y - 80;
    element.style.left = x - 80;
}

function zoomOut()
{
    var element = document.getElementById("overlay");
    element.style.visibility = "hidden";
}

Answer 1

这对我有用：（这里是 JSFiddle）

#imgZoom {
    height: 300;
}
img#imgZoom:hover {
    position: relative;
    -webkit-transform: scale(1.5);
    -ms-transform: scale(1.5);
    -o-transform: scale(1.5);
    transform: scale(1.5);
    z-index: 1000;
}

您也可以添加这个以获得炫酷的过渡效果：

* {
    -webkit-transition: all 0.5s ease-in-out;
    -moz-transition: all 0.5s ease-in-out;
    -ms-transition: all 0.5s ease-in-out;
    -o-transition: all 0.5s ease-in-out;
    transition: all 0.5s ease-in-out;
}

*此外，您不仅可以对图像应用相同的逻辑，还可以对 div 应用相同的逻辑。

Answer 2

您可以通过在鼠标悬停时播放背景位置来实现，只需在鼠标悬停时移动背景位置即可 DEMO

function zoomIn(event) {
  var element = document.getElementById("overlay");
  element.style.display = "inline-block";
  var img = document.getElementById("imgZoom");
  var posX = event.offsetX ? (event.offsetX) : event.pageX - img.offsetLeft;
  var posY = event.offsetY ? (event.offsetY) : event.pageY - img.offsetTop;
  element.style.backgroundPosition = (-posX * 4) + "px " + (-posY * 4) + "px";

}

function zoomOut() {
  var element = document.getElementById("overlay");
  element.style.display = "none";
}

#overlay {
  border: 1px solid black;
  width: 200px;
  height: 200px;
  display: inline-block;
  background-image: url('https://via.placeholder.com/400.png');
  background-repeat: no-repeat;
}

<img id="imgZoom" width="200px" height="200px" onmousemove="zoomIn(event)" onmouseout="zoomOut()" src="https://via.placeholder.com/200.png">
<div id="overlay" onmousemove="zoomIn(event)"></div>

Answer 3

function zoomIn(event) {
  var element = document.getElementById("overlay");
  element.style.display = "inline-block";
  var img = document.getElementById("imgZoom");
  var posX = event.offsetX ? (event.offsetX) : event.pageX - img.offsetLeft;
  var posY = event.offsetY ? (event.offsetY) : event.pageY - img.offsetTop;
  element.style.backgroundPosition = (-posX * 4) + "px " + (-posY * 4) + "px";

}

function zoomOut() {
  var element = document.getElementById("overlay");
  element.style.display = "none";
}

#overlay {
  border: 1px solid black;
  width: 100px;
  height: 100px;
  display: inline-block;
  background-image: url('http://ginger-mum.com/wp-content/uploads/2015/10/3633-1269758855-0da5042c33400a811a5d766be4579cb8.jpg');
  background-repeat: no-repeat;
}

<img id="imgZoom" width="200px" height="200px" onmousemove="zoomIn(event)" onmouseout="zoomOut()" src="http://ginger-mum.com/wp-content/uploads/2015/10/3633-1269758855-0da5042c33400a811a5d766be4579cb8.jpg">
<div id="overlay" onmousemove="zoomIn(event)"></div>

Answer 4

试试这个

window.addEventListener("load", imageZoom("my-image"));

function imageZoom(imgID) {
    let img, lens, result, cx, cy;
    img = document.getElementById(imgID);
    result = document.getElementById("my-result");
    lens = document.querySelector(".img-zoom-lens");
    cx = result.offsetWidth / lens.offsetWidth;
    cy = result.offsetHeight / lens.offsetHeight;
    result.style.backgroundImage = "url('" + img.src + "')";
    result.style.backgroundSize = (img.width * cx) + "px " + (img.height * cy) + "px";
    lens.addEventListener("mousemove", moveLens);
    img.addEventListener("mousemove", moveLens);
    lens.addEventListener("touchmove", moveLens);
    img.addEventListener("touchmove", moveLens);
    function moveLens(e) {
        let pos, x, y;
        e.preventDefault();
        pos = getCursorPos(e);
        x = pos.x - (lens.offsetWidth / 2);
        y = pos.y - (lens.offsetHeight / 2);
        if (x > img.width - lens.offsetWidth) {x = img.width - lens.offsetWidth;}
        if (x < 0) {x = 0;}
        if (y > img.height - lens.offsetHeight) {y = img.height - lens.offsetHeight;}
        if (y < 0) {y = 0;}
        lens.style.left = x + "px";
        lens.style.top = y + "px";
        result.style.backgroundPosition = "-" + (x * cx) + "px -" + (y * cy) + "px";
    }
    function getCursorPos(e) {
        let a, x = 0, y = 0;
        e = e || window.event;
        a = img.getBoundingClientRect();
        x = e.pageX - a.left;
        y = e.pageY - a.top;
        x = x - window.pageXOffset;
        y = y - window.pageYOffset;
        return {x : x, y : y};
    }
}

// Function to change Images
(function () {
  let originalImg = document.querySelector("#my-image");
  let galleryImg = document.querySelector(".img-gallery").children;

  for(let i = 0; i < galleryImg.length; i++) {
    galleryImg[i].onclick = function() {
      originalImg.setAttribute("src", this.getAttribute("src"));
      imageZoom("my-image");
    };
  }
})();

* {
  box-sizing: border-box;
  font-family: sans-serif;
}

.img-container {
  position: relative;
  display: flex;
  justify-content: space-between;
}

.img-zoom-lens {
  position: absolute;
  border: 3px solid rgb(0, 126, 255);
  background-color: rgba(0, 126, 255, .2);
  width: 40px;
  height: 40px;
}

#my-image {
  max-width: 50%;
  height: 300px;
}

.img-zoom-result {
  border: 1px solid #f1f1f1;
  width: 300px;
  height: 300px;
}

.img-gallery {
  margin: 16px 0;
}

.img-gallery img {
  display: inline-block;
  cursor: pointer;
  width: 110px;
  height: 110px;
  border: 1px solid #ccc;
  padding: 4px;
  margin-right: 8px;
}

.img-gallery img:active {
  box-shadow: 0 0 0.1rem 0.1rem rgba(38,143,255,.5);
}

.img-gallery img:focus {
  box-shadow: 0 0 0.1rem 0.1rem rgba(38,143,255,.5);
}

<h1>Create an Image Zoom</h1>

<div class="img-container">
  <div class="img-zoom-lens"></div>
  <img id="my-image" src="https://parrot-tutorial.com/images/carousel_red3.jpg">
  <div id="my-result" class="img-zoom-result"></div>
</div>

<p>Choose more images:</p>
<div class="img-gallery">
    <img src="https://parrot-tutorial.com/images/avatar.jpg">
    <img src="https://parrot-tutorial.com/images/bottleship.jpg">
    <img src="https://parrot-tutorial.com/images/toxic.jpg">
</div>

参考：Create an Image Zoom

Javascript：在没有 Jquery 或插件的情况下放大鼠标悬停

Javascript: Zoom in on mouseover WITHOUT Jquery or plugins

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