makestatic-emit-gzip/index.js

Emits static gzip files

const when = require('when')
const zlib = require('zlib')

/**
 *  Creates static `.gz` files for each output file.
 *
 *  This plugin is enabled by the `core-standard` configuration when the
 *  `gzip` option is given.
 *
 *  @class EmitGzip
 *
 *  @see /docs/api/cli/ Command Line Interface
 *  @see /docs/api/core-standard/ Core Standard
 */
class EmitGzip {

  /**
   *  For each file compress the file `content` using the `zlib` module and
   *  add a new file to the pipeline with a `.gz` file extension.
   *
   *  Before this plugin is executed files must have been assigned a `content`
   *  buffer.
   *
   *  Files marked as `transient` are ignored.
   *
   *  If the `gzip` context option is not set this function call is a noop.
   *
   *  @function sources
   *  @member EmitGzip
   *
   *  @param {Object} file the file being processed.
   *  @param {Object} context the processing context.
   *  @param {Object} conf the plugin configuration.
   */
  sources (file, context, conf = {}) {
    const log = context.log
    const opts = context.options

    if (file.transient || opts.gzip === false) {
      return
    }

    return when.promise((resolve, reject) => {
      zlib.gzip(file.content, conf, (err, content) => {
        /* istanbul ignore next: not going to mock zlib error */
        if (err) {
          return reject(err)
        }

        const ext = '.gz'
        let key = file.output + ext

        /* istanbul ignore next: not going to mock webpack integration here */
        if (opts.pack) {
          key = file.relative(
            context.options.output, true, file.output) + ext
        }

        const gzip = context.getFile(
          {output: key, content: content, name: file.name + ext})

        log.info('[gzip] %s', gzip.output)

        context.list.add(gzip)

        resolve()
      })
    })
  }
}

module.exports = EmitGzip