bestikk-uglify/index.js

A simple tool to uglify JavaScript files based on Google Closure Compiler

'use strict'
const log = require('bestikk-log')
const childProcess = require('child_process')

const javaSemanticVersion = function () {
  const result = childProcess.execSync('java -version 2>&1', { encoding: 'utf8' })
  return extractJavaSemanticVersion(result)
}

const extractJavaSemanticVersion = function (input) {
  const lines = input.split('\n')
  let javaVersionLine
  for (const line of lines) {
    if (line.startsWith('java version') || line.startsWith('openjdk version')) {
      javaVersionLine = line
    }
  }
  if (javaVersionLine) {
    const javaVersion = javaVersionLine.match(/"(.*?)"/i)[1]
    let semanticVersion
    if (javaVersion.indexOf('.') === -1) { // Check if version is formatted as number
      semanticVersion = [null, javaVersion, 0, 0]
    } else {
      semanticVersion = javaVersion.match(/([0-9]+)\.([0-9]+)\.([0-9]+)(_.*)?/i)
    }
    const major = parseInt(semanticVersion[1])
    const minor = parseInt(semanticVersion[2])
    const patch = parseInt(semanticVersion[3])
    const meta = semanticVersion[4]
    if (major === 1) {
      return {
        major: minor,
        minor: patch,
        patch: parseInt(meta.replace(/_/g, ''))
      }
    } else {
      return {
        major,
        minor,
        patch
      }
    }
  }
  throw new Error('Unable to find the java version in: ' + lines)
}

const checkRequirements = function () {
  // Java 8 or higher must be available in PATH
  try {
    const semanticVersion = javaSemanticVersion()
    if (semanticVersion.major < 8) {
      log.error('Closure Compiler requires Java 8 or higher')
      return false
    }
  } catch (e) {
    log.error('error: ' + e)
    log.error('\'java\' binary is not available in PATH')
    return false
  }
  return true
}

class Uglify {
  constructor (args) {
    this.requirementSatisfied = checkRequirements()
    this.compilerJar = 'closure-compiler-v20190215.jar'
    this.args = args || ['--warning_level=QUIET']
  }

  async minify (source, destination) {
    if (this.requirementSatisfied) {
      return new Promise((resolve, reject) => {
        // eslint-disable-next-line n/no-path-concat
        childProcess.exec(`java -jar ${__dirname}/${this.compilerJar} ${this.args.join(' ')} --js_output_file=${destination} ${source}`, error => {
          if (error) {
            log.error('error: ' + error)
            return reject(error)
          }
          return resolve({})
        })
      })
    }
    log.warn('Requirements are not satisfied (see previous errors), skipping minify task')
    return {}
  }
}

module.exports = Uglify
module.exports._extractJavaSemanticVersion = extractJavaSemanticVersion