为什么 Bootstrap 4 张卡片图像使用 data-src 而不是图像标签的 src？
Why does Bootstrap 4 card images use data-src and not src for image tags?
在下面的演示代码中它使用了data-src但没有使用img src。图像是如何应用的？ javascript 是否以某种方式修改了它？
http://v4-alpha.getbootstrap.com/components/card/
<div class="card">
<img class="card-img-top" data-src="..." alt="Card image cap">
<div class="card-block">
<h4 class="card-title">Card title</h4>
<p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p>
<a href="#" class="btn btn-primary">Button</a>
</div>
</div>
Bootstrap 4 文档使用 holder.js，参见 http://imsky.github.io/holder/
另见：https://github.com/imsky/holder#usage
Include holder.js in your HTML:
Holder will then process all images with a specific src attribute,
like this one:
The above tag will render as a placeholder 300 pixels wide and 200
pixels tall.
To avoid console 404 errors, you can use data-src instead of src.
包含持有人
在下面的演示代码中它使用了data-src但没有使用img src。图像是如何应用的？ javascript 是否以某种方式修改了它？
http://v4-alpha.getbootstrap.com/components/card/
<div class="card">
<img class="card-img-top" data-src="..." alt="Card image cap">
<div class="card-block">
<h4 class="card-title">Card title</h4>
<p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p>
<a href="#" class="btn btn-primary">Button</a>
</div>
</div>
Bootstrap 4 文档使用 holder.js，参见 http://imsky.github.io/holder/
另见：https://github.com/imsky/holder#usage
包含持有人Include holder.js in your HTML:
Holder will then process all images with a specific src attribute, like this one:
The above tag will render as a placeholder 300 pixels wide and 200 pixels tall.
To avoid console 404 errors, you can use data-src instead of src.