Resize retina files to normal with gulp

gulpfile.coffee

gulp = require('gulp')
newer = require('gulp-newer')
unretina = require('gulp-unretina')
rename = require('gulp-rename')

###*
# Transforms the path from e.g. asset_2x.png to asset.png
# @param {String} suffix The suffix to remove
###
transformPath = (suffix) ->
  (relativePath) ->
    p = relativePath.split('.')
    p[0].substring(0, p[0].length - suffix.length) + '.' + p[1]

gulp.task 'unretina', ->
  gulp.src('./src/**/*_2x.{png,jpg}')
    .pipe(newer(
      dest: './dist'
   	  map: transformPath('_2x')
    ))
    .pipe unretina(suffix: '_2x')
    .pipe gulp.dest('./dist')

gulpfile.js

var gulp = require('gulp');
var newer = require('gulp-newer');
var unretina = require('gulp-unretina');
var rename = require('gulp-rename');

/**
 * Transforms the path from e.g. asset_2x.png to asset.png
 * @param {String} suffix The suffix to remove
 */
function transformPath(suffix) {
  return function(relativePath) {
    var p = relativePath.split('.');
    return p[0].substring(0, p[0].length - suffix.length) + '.' + p[1];
  }
}

gulp.task('unretina', function () {
  return gulp.src('./src/**/*_2x.{png,jpg}')
    .pipe(newer({
      dest: './dist',
      map: transformPath('_2x')
    }))
    .pipe(unretina({
      suffix: '_2x'
    }))
    .pipe(gulp.dest('./dist'));
});