使用元素可以更好地處理響應(yīng)式圖片，它通過多個<source>和一個實現(xiàn)根據(jù)屏幕尺寸、分辨率及格式支持加載最合適的圖片。具體包括：1. 不同屏幕尺寸下的不同裁剪圖；2. 支持現(xiàn)代格式如WebP或AVIF；3. 高分辨率設(shè)備的高清圖片。結(jié)構(gòu)上需依次使用<source>定義條件與圖片源，並以作為回退方案，同時注意始終包含、使用srcset而非src、可通過type指定格式以確保兼容性。此外應(yīng)合理設(shè)置斷點、優(yōu)化圖片並保留有效alt文本，而簡單場景下也可僅用img srcset實現(xiàn)響應(yīng)式。

Using the <picture></picture> element is one of the best ways to handle responsive images on the web. It gives you more control over which image gets shown based on screen size, resolution, and even format support. Let's break it down into what you actually need to know and how to use it effectively.

What the <picture></picture> element does

The <picture></picture> element works like a container that holds multiple <source></source> elements along with a fallback <img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175233903669148.jpeg" class="lazy" alt="如何將圖片元素用於響應(yīng)圖像？" > . Browsers check each <source></source> in order and load the first one that matches the current device conditions — things like screen width or pixel density.

It's especially useful when you want:

• Different crops of an image for different screen sizes
• Modern image formats (like WebP or AVIF) for supported browsers
• High-resolution versions for retina displays

This isn't just about saving bandwidth — it's about showing the right image at the right time without sacrificing quality or layout.

How to structure your <picture></picture> tag

Here's a basic example:

 <picture>
  <source srcset="large.jpg" media="(min-width: 1024px)">
  <source srcset="medium.jpg" media="(min-width: 768px)">
  <img src="/static/imghw/default1.png"  data-src="small.jpg"  class="lazy" alt="A responsive image">
</picture>

Each <source> defines a different image ( srcset ) and a condition ( media ). The browser picks the first matching source, or falls back to the <img src="/static/imghw/default1.png" data-src="image.jpg" class="lazy" alt="如何將圖片元素用於響應(yīng)圖像？" > if none match.

A few things to keep in mind:

• Always include an <img src="/static/imghw/default1.png" data-src="image.jpg" class="lazy" alt="如何將圖片元素用於響應(yīng)圖像？" > tag as the last child — it's required.
• Use srcset instead of src inside <source> .
• You can also use type attribute to specify image formats.

When to use type and why it matters

If you're using next-gen image formats like WebP or AVIF, not all browsers support them (though most modern ones do). That's where the type attribute comes in handy:

 <picture>
  <source srcset="image.avif" type="image/avif">
  <source srcset="image.webp" type="image/webp">
  <img src="/static/imghw/default1.png"  data-src="image.jpg"  class="lazy" alt="Fallback image">
</picture>

In this case, the browser checks if it supports AVIF first. If not, it tries WebP. If neither is supported, it loads the JPG version. This way, users get the best possible image format their browser supports — no extra work needed from you.

You don't have to worry about ordering too much here — browsers will pick the best match automatically based on support.

Tips for getting the most out of <picture></picture>

• Use meaningful breakpoints — Don't copy other people's media queries blindly. Use breakpoints that make sense for your design and content.
• Test across devices — Make sure your images look good and load correctly on mobile, tablet, and desktop.
• Don't forget alt text — The <img alt="如何將圖片元素用於響應(yīng)圖像？" > still needs proper alt text for accessibility and SEO.
• Optimize your images — Even though <picture></picture> helps with responsiveness, always compress and resize your images before putting them online.

Also, keep in mind that while <picture></picture> is powerful, it's not always necessary. For simple size changes without different crops or formats, img srcset and sizes might be enough.

基本上就這些。

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