index.js

#!/usr/bin/env node
var fs = require('fs')
var path = require('path')
var dom = require('cheerio')
var args = process.argv.slice(2)
var $ = dom.load('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="0" height="0" style="display:none;"></svg>')
var dir
var fileName
var svgNode
var symbolNode

function parse (file) {
  if (path.extname(file) === '.svg') {
    fileName = file.slice(0, -4)
    file = fs.readFileSync(path.join(dir, file), 'utf8')
    svgNode = $(file)
    symbolNode = $('<symbol></symbol>')
    symbolNode.attr('viewBox', svgNode.attr('viewbox'))
    symbolNode.attr('id', fileName)
    symbolNode.append(svgNode.contents())
    symbolNode
      .children()
      .each(function (i, kid) {
        $(kid)
          .removeAttr('fill')
          .removeAttr('stroke')
          .removeAttr('style')
      })
    $('svg').append(symbolNode)
  }
}

if (args && args.length) {
  dir = args[0]
  fs.readdir(dir, function (err, files) {
    if (err) {
      process.stderr.write(err)
      return
    }
    files.forEach(parse)
    process.stdout.write($.html())
  })
} else {
  process.stderr.write('Directory not found.')
}