Use svg symbols in React, works without changes with SSR

App.jsx

import arrow from 'symbol-loader!arrow.svg'

const App = () => (
  <SymbolProvider>
    <svg><Use symbol={arrow} /></svg>
  </SymbolProvider>
)

symbol-loader.js

'use strict'

const path = require('path')
const SVGCompiler = require('svg-baker')
const svgCompiler = new SVGCompiler()

const getFileId = filePath => path.parse(filePath).name

module.exports = function(content) {
	const resourceQuery = this.resourceQuery || ''
	const done = this.async()
	const id = getFileId(this.resourcePath)

	svgCompiler
		.addSymbol({id, content, path: this.resourcePath + resourceQuery})
		.then(symbol => {
			const wrappedId = JSON.stringify(symbol.id)
			const text = JSON.stringify(symbol.render())

			done(null, `module.exports = {id: ${wrappedId}, text: ${text}}`)
		})
		.catch(done)
}

SymbolProvider.jsx

import React, {Component} from 'react'
import PropTypes from 'prop-types'
import Symbols from 'plugins/icons/Symbols'

class SymbolProvider extends Component {
	static childContextTypes = {
		icons: PropTypes.object,
	}

	uses = {}
	childCtx = {
		icons: {
			register: fn => (this.onUpdate = fn),
			unRegister: fn => {
				if (this.onUpdate === fn) this.onUpdate = null
			},
			addSymbol: symbol => {
				const ref = this.uses[symbol.id]
				if (ref) {
					if (ref.symbol !== symbol) {
						console.error(new Error(`Symbol ID ${symbol.id} has to be unique`))
						return
					}
					ref.count++
				} else {
					this.uses[symbol.id] = {symbol, count: 1}
				}
				if (this.onUpdate) this.onUpdate()
			},
			removeSymbol: symbol => {
				const ref = this.uses[symbol.id]
				if (!ref) {
					console.log(new Error(`refcount error for symbol ${symbol.id}`))
					return
				}
				ref.count--
				if (ref.count < 1) delete this.uses[symbol.id]
			},
			getSymbols: () =>
				Object.values(this.uses)
					.map(s => s.symbol.text)
					.join(''),
		},
	}
	getChildContext() {
		return this.childCtx
	}
	render() {
		const {children} = this.props
		return (
			<React.Fragment>
				{children}
				<Symbols />
			</React.Fragment>
		)
	}
}

export default SymbolProvider

Symbols.jsx

import React, {Component} from 'react'
import PropTypes from 'prop-types'

class SvgSymbols extends Component {
	static contextTypes = {
		icons: PropTypes.object,
	}
	update = () => this.forceUpdate()
	componentDidMount() {
		this.context.icons.register(this.update)
	}
	componentWillUnmount() {
		this.context.icons.unregister(this.update)
	}

	render() {
		const {getSymbols} = this.context.icons
		return (
			<svg
				xmlns="http://www.w3.org/2000/svg"
				xmlnsXlink="http://www.w3.org/1999/xlink"
				dangerouslySetInnerHTML={{__html: getSymbols()}}
			/>
		)
	}
}

export default SvgSymbols

Use.jsx

import React, {Component} from 'react'
import PropTypes from 'prop-types'

class Use extends Component {
	static contextTypes = {
		icons: PropTypes.object,
	}
	updateSymbols(oldSymbol, newSymbol) {
		if (oldSymbol === newSymbol) return
		const {addSymbol, removeSymbol} = this.context.icons
		if (oldSymbol) removeSymbol(oldSymbol)
		if (newSymbol) addSymbol(newSymbol)
	}
	componentWillMount() {
		this.updateSymbols(null, this.props.symbol)
	}
	componentWillReceiveProps(nextProps) {
		this.updateSymbols(this.props.symbol, nextProps.symbol)
	}
	componentWillUnmount() {
		this.updateSymbols(this.props.symbol, null)
	}

	render() {
		const {symbol} = this.props
		if (!symbol) return false
		return <use xlinkHref={'#' + symbol.id} />
	}
}

export default Use

This works because:

• <use> can refer to symbols that follow it in the page
• the SSR first renders the entire page, so by the time it renders the <Symbols/>, all the symbols used in the page are known