svg-extract-images.js

const fs = require('fs')
const path = require('path')
const matcher = /xlink:href="data:(img|image)\/([a-z]+);base64,([^"]+)"/gi
const file = process.argv.pop()
const noop = function() {}

fs.readFile(file, 'utf-8', function (err, data) {
	if (err) return console.error(err)
	const name = path.basename(file, '.svg')
	let newData = data
	let matches, i = 0
	while (matches = matcher.exec(data)) {
		const format = matches[2], encoded = matches[3]
		const img = name + '_' + (i++) + '.' + format
		const contents = Buffer.from(encoded, 'base64')
		fs.writeFile(img, contents, noop)
		newData = newData.replace(matches[0], 'xlink:href="'+img+'"')
	}
	fs.writeFile(name + '_extracted.svg', newData, noop)
})