包含12行JavaScript的现代HTML5灯箱

“Lightbox” effects have been an established UI pattern for a decade, but the vast majority of implementations have been framework-dependent. In previous articles I’ve shown how to create a Lightbox UI using only CSS, although that version lacked controls. By adding the <dialog> element and a dozen lines of vanilla JavaScript, we can recreate a traditional lightbox perfectly:

十年来，“灯箱”效果已经成为一种既定的UI模式，但是绝大多数实现方式都依赖于框架。在之前的文章中，我展示了如何仅使用CSS创建灯箱UI ，尽管该版本缺少控件。通过添加<dialog> element和十几行香草JavaScript ，我们可以完美地重新创建传统的灯箱：

标记 (The Markup)

<nav id="thumbs"><a href="elephant.jpg"><img src="elephant-thumb.jpg" alt></a><a href="taj-mahal.jpg"><img src="taj-mahal-thumb.jpg" alt></a><a href="wise-man.jpg"><img src="wise-man-thumb.jpg" alt></a>
</nav>
<dialog id="cover"><button id="closecover">Close</button><img src="" alt>
</dialog>

The linked images follow the pattern used in my previous “Accessible Image Gallery with Progressive JavaScript” article; the large image inside the <dialog> element is a placeholder that we’ll change later using JavaScript. (alt values have been left blank for the sake of brevity).

链接的图像遵循我以前的“ 带有渐进式JavaScript的可访问图像库 ”文章中使用的模式； <dialog>元素中的大图像是一个占位符，稍后我们将使用JavaScript对其进行更改。 (为简洁起见， alt值保留为空白)。

CSS (The CSS)

@keyframes fadeToNearBlack {to { background: rgba(0,0,0,0.9); }
}
@keyframes goBig { to { opacity: 1; }
}
nav { display: flex;
}
nav a { display: block; flex: 1;
}
nav a img,
dialog img { width: 100%; height: auto;
}
dialog { border: none; opacity: 0; }
dialog button { border: none; background: none; font-size: 1.2rem;
}
dialog[open] {animation: goBig 1s .4s forwards;width: 70%; margin: auto;position: absolute; max-width: 700px;
}
dialog[open]::backdrop { animation: fadeToNearBlack 1s forwards;
}
.backdrop { animation: fadeToNearBlack 1s forwards;
}

The animations will fade in the <dialog> element; the <nav> links are displayed using flexbox to divide them evenly across the page. When visible, the <dialog> element is positioned using a variation on one of the established methods of centering elements when the height of the parent (the <body>, in this case) is unknown. (Vendor prefixes have been dropped for the purpose of clarity).

动画将在<dialog>元素中消失； <nav>链接使用flexbox进行显示，以在页面上平均分配它们。当可见时，当父对象(在这种情况下为<body> )的高度未知时，使用对中元素的一种既定方法对 <dialog>元素进行定位。 (为了清楚起见，已删除了供应商前缀 )。

JavaScript (The JavaScript)

The script goes at the end of the document; other browsers will require an additional polyfill to support the <dialog> element.

该脚本位于文档末尾；其他浏览器将需要附加的polyfill来支持<dialog>元素。

function showImage(e) {e.preventDefault();coverimage.setAttribute("src", this.getAttribute("href"));coverimage.setAttribute("alt", this.querySelector("img").getAttribute("alt"));cover.showModal();
}
document.getElementById("closecover").onclick = function() { coverimage.setAttribute("src", "");cover.close();
}
var imglinks = document.getElementById("thumbs").getElementsByTagName('a'),
cover = document.getElementById("cover"),
coverimage = cover.getElementsByTagName("img")[0];
testdialog=document.createElement("dialog");
testdialog.setAttribute("open", "");
if (!testdialog.open) { dialogPolyfill.registerDialog(cover);
}
for (var i=0; i<imglinks.length; i++) { imglinks[i].onclick = showImage;
}

The script attaches a function to each of the links; when the user clicks on one, it sets the src attribute of the large image in the <dialog> element to the value of the link and shows the modal window; the elements animate due to the CSS we applied earlier. Clicking on the altered <button> element closes the modal. Because the thumbnail images are links, they are also progressive and accessible.

该脚本将函数附加到每个链接。当用户单击一个时，它将<dialog>元素中大图像的src属性设置为链接的值并显示模式窗口；由于我们之前应用了CSS，因此这些元素会动画。单击更改的<button>元素将关闭模式。由于缩略图是链接，因此它们也是渐进的且可访问的。

结论与改进 (Conclusion & Improvements)

There are a few things that could be better; obviously, being able to drop the polyfill once all browsers support the <dialog> element would be good, and the element itself could be animated like the version in my CSS-only example. Centering the element perfectly across different platforms could also be improved: right now, things move around a little more than I would like. I’ll leave that and further enhancements for a future article.

有些事情可能会更好。显然，一旦所有浏览器都支持<dialog>元素，便能够删除polyfill会很好，并且该元素本身也可以像我的纯CSS示例中的版本那样进行动画处理。还可以改善将元素完美地放在不同平台上的中心位置：现在，事情的移动幅度超出了我的期望。在以后的文章中，我将保留该内容和进一步的增强功能。

翻译自: https://thenewcode.com/962/A-Modern-HTML5-Lightbox-in-12-Lines-of-JavaScript