svg-sprites/docs/en/reference.md

Technical reference

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Reference for the configuration, generated API, and behavior of @gromlab/svg-sprites. For step-by-step setup instructions, see the guide for your stack:

• Next.js App Router
• Next.js Pages Router
• React + Vite
• React + Webpack 5

Requirements

• Node.js 18 or newer;
• the package is distributed as ESM and is loaded with import;
• React 18 or 19 is required for generated components and @gromlab/svg-sprites/react;
• for typed package exports, use TypeScript 5+ with moduleResolution: "bundler", "node16", or "nodenext".

Install the package as a development dependency:

npm install --save-dev @gromlab/svg-sprites

CLI and generation modes

The CLI accepts exactly one path: an explicitly selected config file or a directory for config-less generation:

svg-sprites [options] <config-file-or-directory>

Environment	Mode
Static HTML / custom publishing	standalone
Standalone + Vite	standalone@vite
Standalone + Webpack 5	standalone@webpack
React + Vite	react@vite
React + Webpack 5	react@webpack
Next.js App Router + Turbopack	next@app/turbopack
Next.js App Router + Webpack 5	next@app/webpack
Next.js Pages Router + Turbopack	next@pages/turbopack
Next.js Pages Router + Webpack 5	next@pages/webpack

The config file may have any name and use the .ts, .js, or .json extension. The CLI does not discover it by convention: pass the file explicitly. The guides use svg-sprite.config.ts as the recommended name.

When a directory is passed, all settings come from CLI options. When a config file is passed, CLI options override the file. The full order is defaults → config → CLI.

Available options are --mode, --name, --description, --input-folder, repeatable --input-file, plus the --remove-size/--no-remove-size, --replace-colors/--no-replace-colors, --add-transition/--no-add-transition, and --generated-notice/--no-generated-notice pairs. Transform flags override individual fields, while supplying at least one --input-file replaces the complete config inputFiles array.

The mode must match the application's publishing strategy. Bare standalone leaves the public URL to the application; Vite and Webpack modes generate bundler-specific SVG asset integration.

Unified configuration

Each config file defines one independent sprite.

import { defineSpriteConfig } from '@gromlab/svg-sprites'

export default defineSpriteConfig({
  mode: 'next@app/turbopack',
  name: 'app',
  description: 'Shared application icons',
  inputFolder: './local-icons',
  inputFiles: [
    '../../assets/icons/search.svg',
    '../../assets/icons/settings.svg',
  ],
  transform: {
    removeSize: true,
    replaceColors: true,
    addTransition: true,
  },
  generatedNotice: true,
})

Option	Type	Default	Purpose
mode	SpriteMode	None	Generation mode; may be supplied by CLI/API
name	string	Derived from the directory	Name of the sprite, component, and public types
description	string	None	Description for types and the debug manifest
inputFolder	string	./icons	SVG directory relative to the module root
inputFiles	string[]	[]	Paths to individual SVG files relative to the module root
transform	TransformOptions	All enabled	SVG preparation settings
generatedNotice	boolean	true	Full or abbreviated warning in generated files

Sprite name

name is written in kebab-case and must start with an ASCII letter:

app          → AppIcon
file-manager → FileManagerIcon

If name is omitted, the generator derives it from the directory. For a directory named svg-sprite or svg-sprites, the parent directory's name is used.

Icon sources

inputFolder and inputFiles are combined into one set. This lets you keep local SVG files next to a module and add shared icons from other parts of the project without copying them.

If inputFiles is populated and the implicit ./icons directory does not exist, generation uses only the file list. An explicitly configured inputFolder that does not exist is an error.

Only the top level of the directory is scanned. Nested directories are not traversed recursively. For a nested structure, list the exact paths through inputFiles.

Identical absolute paths are deduplicated. Different SVG files with the same file name are treated as a conflict because the public icon name is derived from the basename.

Generated module

After generation, a React or Next.js sprite directory looks like this:

app-icons/
├── .gitignore
├── svg-sprite.config.ts
├── index.ts                         # optional user-owned barrel
└── .svg-sprite/
    ├── state.json
    ├── index.js
    ├── index.d.ts
    ├── icon-data.js
    ├── icon-data.d.ts
    ├── sprite.svg
    ├── svg-sprite.manifest.js
    ├── svg-sprite.manifest.d.ts
    └── react/
        ├── react-component.js
        ├── react-component.d.ts
        └── react-component.module.css

File	Purpose
.svg-sprite/index.js	Production exports for the component and runtime icon-name list
.svg-sprite/index.d.ts	Public declarations for the component, props, styles, and icon-name union
.svg-sprite/svg-sprite.manifest.js	Debug metadata and the asset URL for SpriteViewer
.svg-sprite/sprite.svg	Compiled SVG sprite
.svg-sprite/react/react-component.js	React component runtime without TypeScript or JSX
.svg-sprite/react/react-component.d.ts	React component props, style, and declaration
.svg-sprite/react/react-component.module.css	Styles for the React implementation
.svg-sprite/icon-data.js	Runtime icon-name list and internal IDs
.svg-sprite/*.d.ts	TypeScript declarations for the corresponding JavaScript modules
.svg-sprite/state.json	Mode, contract version, and managed file list

Standalone contracts do not create react/. Bare standalone contains only the runtime asset and deployment-neutral manifest data:

.svg-sprite/
├── state.json
├── sprite.svg
└── svg-sprite.manifest.json

standalone@vite and standalone@webpack additionally create index.*, icon-data.*, and a resolved svg-sprite.manifest.*.

The generator overwrites and deletes only files that contain its marker. If a user file occupies a managed path, generation fails. The root index.ts is user-owned; create a barrel when needed:

export * from './.svg-sprite'

React component and TypeScript

A sprite with name: 'app' exports:

export { AppIcon, appIconNames }
export type { AppIconName, AppIconProps, AppIconStyle }

Icon names

SVG file names become valid icon values:

<AppIcon icon="search" />
<AppIcon icon="unknown" /> // TypeScript error

The runtime list contains the same values:

import { appIconNames } from '@/ui/app-icons'

// readonly ['search', 'settings', 'user']

Names containing spaces or other characters that are unsafe in SVG IDs remain part of the public API. For the internal fragment ID, the generator creates a stable, safe hash:

folder open.svg → icon="folder open" → id="icon-<stable-hash>"

For these names, use the generated component or the id from the debug manifest instead of constructing the fragment ID manually.

SVG attributes

By default, the component renders an <svg> and accepts standard SVG attributes:

<AppIcon
  icon="search"
  width={24}
  height={24}
  color="rebeccapurple"
  className="searchIcon"
  aria-label="Search"
/>

The component does not add accessibility semantics automatically. Pass appropriate aria-* attributes, a role, or a label based on the icon's purpose.

Wrapper

wrapped renders a <span> containing the SVG. In this mode, the remaining props apply to the <span>:

<AppIcon icon="search" wrapped className="iconWrapper" />

Typed CSS custom properties

AppIconStyle extends CSSProperties and supports properties in the form --icon-color-N:

<AppIcon
  icon="user"
  style={{
    '--icon-color-1': '#2563eb',
    '--icon-color-2': '#dbeafe',
  }}
/>

Multiple sprites

Each directory with a configuration creates an independent component, types, manifest, and SVG asset:

app-icons       → AppIcon       → shared icons
analytics-icons → AnalyticsIcon → analytics page icons
editor-icons    → EditorIcon    → editor icons

The same source SVG can be added to multiple configurations through inputFiles. You do not need to copy the file into each sprite directory.

For multiple sprites, add a separate CLI command for each directory or combine the commands in a shared npm script.

Formats and rendering methods

All current modes generate the stack format.

Format	<svg><use>	<img>	CSS background
stack	Yes	Yes	Yes

Generated component

For React and Next.js, use the generated component. It knows the internal IDs, constructs the URL, and provides a TypeScript API:

<AppIcon icon="search" width={24} height={24} />

Manually with <svg><use>

How you obtain spriteUrl depends on the bundler.

Static HTML after the application publishes .svg-sprite/sprite.svg:

<svg aria-hidden="true">
  <use href="/assets/icons.svg#search"></use>
</svg>

Standalone Vite/Webpack provides generated getIconsIconHref() and an internal ID map. Do not construct fragments from unsafe file names manually.

Vite:

import spriteUrl from './.svg-sprite/sprite.svg?no-inline'

Webpack 5, Turbopack, and Next.js:

const spriteUrl = new URL('./.svg-sprite/sprite.svg', import.meta.url).href

After obtaining the URL, use it in JSX:

<svg width="24" height="24" aria-label="Search">
  <use href={`${spriteUrl}#search`} />
</svg>

For names that are unsafe as SVG IDs, use the internal id from the manifest.

With <img>

<img src={`${spriteUrl}#search`} width={24} height={24} alt="Search" />

An SVG inside <img> is isolated from the page's CSS. Setting color or --icon-color-N on the outer element does not change its internal colors.

With CSS

.icon {
  background: url('./.svg-sprite/sprite.svg#search') center / contain no-repeat;
}

For a single-color silhouette, you can use a mask:

.icon {
  background-color: currentColor;
  mask: url('./.svg-sprite/sprite.svg#search') center / contain no-repeat;
}

A mask does not preserve original colors, gradients, or differences between fill and stroke.

The path in CSS is resolved relative to the CSS file itself. In these examples, the CSS file is next to svg-sprite.config.ts.

Assets and caching

The generated component or standalone facade passes the SVG to the bundler as a separate asset:

• Vite uses a static import with ?no-inline;
• Webpack 5, Turbopack, and Next.js use new URL(..., import.meta.url);
• SVG path data is not serialized into generated JavaScript.

Bare standalone does not participate in an asset pipeline: the application copies or publishes sprite.svg and owns its URL, versioning, and cache policy.

With standard asset naming, the bundler adds a content hash:

/assets/sprite-<hash>.svg

This allows the SVG to be cached separately from JavaScript. Changing React code does not change the sprite contents, while changing icons creates a new asset version.

HTTP cache headers, CDN behavior, and Cache-Control are configured by the application or hosting platform. With Webpack, the final file name depends on the project's assetModuleFilename.

SVG transformations

All transformations are enabled by default and can be configured independently:

Option	Behavior
removeSize	Removes width and height from the root <svg> while preserving an existing viewBox
replaceColors	Replaces detected fill and stroke values with --icon-color-N
addTransition	Adds transitions for fill and stroke to colored elements and generated styles

To disable an individual operation:

export default defineSpriteConfig({
  mode: 'next@app/turbopack',
  transform: {
    removeSize: false,
    replaceColors: false,
    addTransition: false,
  },
})

Source SVG files are not modified. Transformations apply only to the generated sprite contents.

Color management

Monochrome icons

If one color is detected, its fallback becomes currentColor:

stroke="var(--icon-color-1, currentColor)"

Set the color through a prop or CSS:

<AppIcon icon="search" color="rebeccapurple" />

Multicolor icons

Each unique color gets its own custom property with the original color as its fallback:

fill="var(--icon-color-1, #798198)"
fill="var(--icon-color-2, #ffffff)"
fill="var(--icon-color-3, #129d9d)"

You can override only the values you need:

.icon {
  --icon-color-1: #4b5563;
  --icon-color-3: #14b8a6;
}

Limitations

• none, transparent, inherit, unset, and initial are not replaced;
• colors in fill, stroke, and inline style attributes are handled most reliably;
• CSS classes and external stylesheets inside the SVG are not the primary transformation use case;
• url(#...) values may be replaced along with colors, so gradients and patterns require a separate sprite with replaceColors: false;
• masks, filters, and complex internal CSS rules require visual verification;
• page CSS custom properties are available through <svg><use>, but not inside <img> or a CSS background.

For a complex icon, you can disable replaceColors in a separate sprite configuration.

SpriteViewer

The Viewer uses one Shadow DOM Web Component for every mode. React and future framework components are bridges to that same element, so the visuals and behavior are not duplicated.

Bare standalone loads the self-contained browser bundle and supplies the JSON manifest URL and the published SVG URL:

<script
  type="module"
  src="https://unpkg.com/@gromlab/svg-sprites@<version>/dist/viewer-element.js"
></script>

<gromlab-sprite-viewer
  viewer-title="Project icons"
  manifest-url="/app-icons/manifest.json"
  sprite-url="/app-icons/sprite.svg"
></gromlab-sprite-viewer>

viewer-element.js has no additional runtime files and can be copied with the other static assets for self-hosting.

standalone@vite and standalone@webpack register the same element through an npm entry and pass the generated JS manifest through the sources property:

import '@gromlab/svg-sprites/viewer/element'
import type { SpriteViewerElement } from '@gromlab/svg-sprites/viewer'
import spriteManifest from './svg-sprite/.svg-sprite/svg-sprite.manifest.js'

const viewer = document.querySelector<SpriteViewerElement>('gromlab-sprite-viewer')!
viewer.sources = [spriteManifest]

React and Next.js keep the component API:

import { SpriteViewer } from '@gromlab/svg-sprites/react'

It accepts ready-made manifests, remote standalone sources, an array of lazy loaders, or a record in the format returned by import.meta.glob.

Vite:

import { SpriteViewer } from '@gromlab/svg-sprites/react'
import type { SpriteManifestModule } from '@gromlab/svg-sprites/react'

const sources = import.meta.glob<SpriteManifestModule>(
  '/src/**/svg-sprite/.svg-sprite/svg-sprite.manifest.js',
)

export const IconsDebugPage = () => (
  <SpriteViewer sources={sources} title="Project icons" />
)

Webpack and Next.js:

const sources = [
  () => import('@/ui/app-icons/.svg-sprite/svg-sprite.manifest.js'),
  () => import('@/features/analytics/icons/.svg-sprite/svg-sprite.manifest.js'),
]

export const IconsDebugPage = () => (
  <SpriteViewer sources={sources} />
)

The Viewer displays groups, search, viewBox, CSS custom properties, and fallback colors. React/Next manifests get React, SVG, IMG, and CSS tabs; standalone manifests get SVG, IMG, and CSS. You can change color values in the interface and immediately inspect the result.

Viewer theme

By default, colorTheme="auto" follows prefers-color-scheme. You can explicitly pass light or dark:

<SpriteViewer sources={sources} colorTheme="dark" />

To synchronize it with the application theme:

<SpriteViewer
  sources={sources}
  colorTheme={appTheme}
  onColorThemeChange={setAppTheme}
/>

@gromlab/svg-sprites/react contains 'use client' and renders the Web Component host; its internal Shadow DOM is created after the browser runtime loads. In the Next.js App Router, place the Viewer inside a separate Client Component boundary and use it only on a debug route or in an internal tool.

Generated files, Git, and CI

A modern sprite module creates a local .gitignore for:

/.svg-sprite/

Commit the local .gitignore to the repository once. It excludes the other generated files, so generation must run before commands that import the sprite module:

{
  "scripts": {
    "sprites": "svg-sprites src/ui/app-icons/svg-sprite.config.ts",
    "predev": "npm run sprites",
    "prebuild": "npm run sprites",
    "pretypecheck": "npm run sprites"
  }
}

CI must install development dependencies and run the generation script before building or type-checking.

If the sprite directory already contains a user-created .gitignore or a user-owned file inside .svg-sprite, the generator will not overwrite it. The root index.ts remains user-owned and may re-export the generated API.

Troubleshooting

• Missing .svg-sprite/index.js: run the generation script before importing the generated module.
• Source not found: pass an existing config file or sprite module directory.
• Mode missing: add mode to the config or pass --mode.
• Icon missing from the type: check inputFiles, the .svg extension, and the nesting level under inputFolder.
• Name conflict: two different SVG files have the same basename; rename one of them.
• Refusing to overwrite a user file: a file without the generated marker occupies a managed path.
• The icon does not change color: use <svg><use> or the generated component and check replaceColors.
• Webpack emits an incorrect URL: check Asset Modules, output.publicPath, and SVG loaders.
• Static sprite returns 404: check the post-generation copy or server alias, and do not put a filesystem spritePath into HTML.
• The Viewer cannot find the sprite: check the path to .svg-sprite/svg-sprite.manifest.js and run generation before starting the application.
• Build and mode do not match: use the target that corresponds to the actual bundler.

For custom orchestration and low-level compilation, see the Programmatic API.