gulpfile.js

gulp.task('ng-template-watch', function () {
  gulp
    .src('path/**/*.html')
    .pipe(through2.obj(function(file, _, cb){
      file.path += ".ts";
      var prefix = 'var t =';
      var suffix = ';\nexport default t;\n';
      var newC = prefix + JSON.stringify(file.contents.toString()) + suffix;
      file.contents = new Buffer(newC);
      this.push(file);
      cb();
    }))
    .pipe(gulp.dest('path/'))
    ;
});