Three env vars for options:
  WITH_PROJ4
  WITH_GEOTIFF
  WITH_VECTORTILE



npm init
npm install ol
npm install webpack webpack-cli --save-dev

$npm i @babel/core babel-loader @babel/preset-env --save-dev
# add .babelrc and rules in webpack.config.sj

new Date()
  .toISOString()
  .replace(/T[\w\W]+?$/, '') // Delete from "T" to end

npx browserslist # show current results of .browserslistrc query