code: function watch(globs, options) {
      options.delay = 1000
  
      chokidar
          .watch(globs, { persistent: true, ignoreInitial: true })
          .on("add", () => generate(globs, options))
          .on("unlink", () => generate(globs, options))
          .on("change", () => generate(globs, options))
          .on("error", (err) => console.error(`ERROR: ${err.message}`))
          .on("ready", () => {
              if (options.verbose) {
                  console.log(`Be watching ${globs.join(", ")}`)
              }
          })
  
      // In order to kill by the test harness.
      process.on("message", () => {
          process.exit(0)
      })
  }
docs: Generate appcache manifest for each change.
  
  @param {string[]} globs - The globs which specifies the target files.
  @param {object} options - The option object.
  @returns {void}
  @private