A terser script to minify all javascript files in a directory

terser.js

const fs = require('fs')
const {sync: globSync} = require('glob')
const filesize = require('filesize')
const Terser = require('terser')
const options = require(process.env.TERSER_CONFIG || './terserrc.json')

const getSize = (file) => {
  const {size} = fs.statSync(file)
  return filesize(size)
}

const files = globSync(`${process.env.TERSER_DIST_PATH || './dist'}/*.js`)
files.map(file => {
  console.log(`Minifying ${file} (${getSize(file)})`)
  const terserResult = Terser.minify(fs.readFileSync(file, 'utf8'), options)
  if (terserResult.error) {
    console.log(`Minifying ${file} error.`, terserResult.error)
  }
  else {
    fs.writeFileSync(file, terserResult.code, 'utf8');
    console.log(`Minifying ${file} (${getSize(file)}) success.`)
  }
})

terserrc.json

{
  "parse": {
    "ecma": 8
  },
  "compress": {
    "ecma": 5,
    "warnings": false,
    "arrows": false,
    "collapse_vars": false,
    "comparisons": false,
    "computed_props": false,
    "hoist_funs": false,
    "hoist_props": false,
    "hoist_vars": false,
    "inline": false,
    "loops": false,
    "negate_iife": false,
    "properties": false,
    "reduce_funcs": false,
    "reduce_vars": false,
    "switches": false,
    "toplevel": false,
    "typeofs": false,
    "booleans": true,
    "if_return": true,
    "sequences": true,
    "unused": true,
    "conditionals": true,
    "dead_code": true,
    "evaluate": true
  },
  "mangle": {
    "safari10": true
  },
  "output": {
    "ecma": 5,
    "comments": false,
    "ascii_only": true
  }
}