Experimental SVG optimization

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Type: boolean | object
Default: false

追加： astro@5.16.0

This experimental feature enables automatic optimization of your SVG components using SVGO during build time.

When enabled, your imported SVG files used as components will be optimized for smaller file sizes and better performance while maintaining visual quality. This can significantly reduce the size of your SVG assets by removing unnecessary metadata, comments, and redundant code.

To enable this feature with default settings, set it to true in your Astro config:

import { defineConfig } from "astro/config"

export default defineConfig({
  experimental: {
    svgo: true
  }
})

Usage

No change to using SVG components is required to take advantage of this feature. With experimental svgo enabled, all your SVG component import files will be automatically optimized:

---
import Logo from '../assets/logo.svg';
---

<Logo />

The SVG will be optimized during the build process, resulting in smaller file sizes in your production build.

Note that this optimization applies to every SVG component import in your project. It is not possible to opt out on a per-component basis.

Configuration

You can pass an SVGO configuration object to customize optimization behavior:

export default defineConfig({
  experimental: {
    svgo: {
      multipass: true,
      floatPrecision: 2,
      plugins: [
        'preset-default',
        'removeXMLNS',
        {
          name: "removeXlink",
          params: {
            includeLegacy: true
          }
        }
      ]
    }
  }
})

`plugins`

Type: Array<string | PluginConfig>
Default: []

An array of SVGO plugins that will be used to optimize your SVG component imports.

This can include SVGO’s preset-default plugin collection, individual built-in plugins, or custom plugins.

To use a plugin’s default configuration, add its name to the array. If you need more control, use the overrides parameter to customize specific plugins within preset-default, or pass an object with a plugin’s name to override its individual parameters.

export default defineConfig({
  experimental: {
    svgo: {
      plugins: [
        {
          name: 'preset-default',
          params: {
            overrides: {
              convertPathData: false,
              convertTransform: {
                degPrecision: 1,
                transformPrecision: 3
              },
              inlineStyles: false
            },
          },
        },
        'removeXMLNS',
        {
          name: "removeXlink",
          params: {
            includeLegacy: true
          }
        }
      ]
    }
  }
})

Other configuration options

There are a few SVGO configuration options, especially floatPrecision and multipass, that can be passed directly to your config object:

export default defineConfig({
  experimental: {
    svgo: {
      multipass: true,
      floatPrecision: 2
    }
  }
})

The multipass option sets whether to run the optimization engine multiple times until no further optimizations are found. The floatPrecision option sets the number of decimal places to preserve globally, but can be overridden for a specific plugin by specifying a custom value in its params property.

Common use cases

SVGO provides an extensive default plugin list with opinionated optimizations. While using this preset is more convenient than adding each plugin individually, you may need to customize it further. For example, it may remove items or clean up too aggressively for your situation, especially when using animations.

Preserve specific attributes

You may want to preserve certain SVG attributes and elements, such as <style>, that SVGO inlines or removes by default:

export default defineConfig({
  experimental: {
    svgo: {
      plugins: [
        {
          name: 'preset-default',
          params: {
            overrides: {
              inlineStyles: false, // Preserve style elements for CSP hashing
              removeDesc: false // Keep element regardless of contents
            }
          }
        }
      ]
    }
  }
})

Remove specific elements

You can configure plugins to remove specific unwanted elements like metadata or hidden layers. Note that many plugins are already included in preset-default, so you typically only need to configure their behavior:

export default defineConfig({
  experimental: {
    svgo: {
      plugins: [
        {
          name: 'preset-default',
          params: {
            overrides: {
              removeHiddenElems: {
                isHidden: false,
                displayNone: false
              }
            },
          },
        },
        'removeRasterImages'
      ]
    }
  }
})

Optimize for inlining in modern HTML5

Inline SVG does not require the xmlns attribute and can be safely converted to the SVG 2 specification. The removeXMLNS and removeXlink plugins are recommended for this purpose:

export default defineConfig({
  experimental: {
    svgo: {
      plugins: [
        'preset-default',
        'removeXMLNS',
        {
          name: "removeXlink",
          params: {
            includeLegacy: true
          }
        }
      ]
    }
  }
})

How it works

SVG optimization happens during the build process, not at runtime:

In development mode, SVG files are not optimized to ensure faster rebuild times and a smoother development experience.
In production builds, all imported SVG files are optimized once during the build process, resulting in smaller file sizes.
There is no runtime overhead - optimized SVGs are served as pre-processed static assets.

While the optimization process may slightly increase your build times, the result is smaller file sizes and faster page loads for your users.