clase51.md

Máster en Programación FullStack con JavaScript y Node.js

JS, Node.js, Frontend, Backend, Firebase, Express, Patrones, HTML5_APIs, Asincronía, Websockets, Testing

Clase 51

Grunt

//export default grunt => {
module.exports = grunt => {

grunt.initConfig({
  jshint: {
    files: ['Gruntfile.js', 'src/**/*.js', 'test/**/*.js'],
    options: {
      globals: {
        jQuery: true
      }
    }
  },
  watch: {
    files: ['<%= jshint.files %>'],
    tasks: ['jshint']
  }
});

grunt.loadNpmTasks('grunt-contrib-jshint');
grunt.loadNpmTasks('grunt-contrib-watch');
grunt.registerTask('default', ['jshint']);

};

Caractísticas

• Filosofía de configuración sobre codigo
• Basado en archivos temporales
• Ecosistema fuerte
• Poco flexible para cosas fuera de lo común
• Ficheros de configuración sobredimensionados
• Facilmente se desactualiza

Instalación

• Instalamos Gulp global

npm install -g grunt-cli

• Incluimos la dependencia en package.json

npm install grunt --save-dev

Tareas por defecto

• Creamos gruntfile.js y encapsulamos
• Definición

module.exports = grunt => {
  //... resto del código de grunt...
};

• Instanciamos la configuración

module.exports = grunt => {
  grunt.initConfig({
    //...resto de configuración...
  })
  //... resto del código de grunt...
};

• Cargamos las dependencias (plugins)...

module.exports = grunt => {
  grunt.initConfig({
    //...resto de configuración...
  })
  //... resto del código de grunt...
};

grunt.loadNpmTasks('grunt-contrib-NOMBRE-PLUGIN');
grunt.loadNpmTasks('grunt-contrib-NOMBRE-PLUGIN');
//... 

• Creamos la tarea por defecto

module.exports = grunt => {
  grunt.initConfig({
    jshint: {
      files: ['Gruntfile.js', 'src/**/*.js', 'test/**/*.js'],
      options: {
        // options here to override JSHint defaults
        globals: {
          jQuery: true,
          console: true,
          module: true,
          document: true
        }
      }
    }
  })
};

grunt.loadNpmTasks('grunt-contrib-jshint');
grunt.registerTask('default', ['jshint']);

• Creamos tarea watch...

module.exports = grunt => {
  grunt.initConfig({
    jshint: {
      files: ['Gruntfile.js', 'src/**/*.js', 'test/**/*.js'],
      options: {
        // options here to override JSHint defaults
        globals: {
          jQuery: true,
          console: true,
          module: true,
          document: true
        }
      }
    },
    watch: {
      files: ['<%= jshint.files %>'],
      tasks: ['jshint']
    }
  })
};

grunt.loadNpmTasks('grunt-contrib-jshint');
grunt.registerTask('default', ['jshint']);

Lanzamiento

• Lanzar la tarea por defecto grunt
• Lanzar el watch grunt watch
• lanzar una tarea personalizada grunt TAREA

Grunt: Plugins

• The 26 grunt plugins we use at qrator.com | Andy's Blog
• Living list of most useful plugins for Grunt
• 6 essential Grunt plugins you should be using | Creative Bloq
• 7 Essential Plug-ins for those New to GruntJS - Web Design Ledger
• Essential Grunt Plugins - Donna Peplinskie
• Psychedelic Grunt Plugins - Web Design Weekly
• 5 Grunt Plugins for a Better Workflow | Chase Adams
• Building a Better Grunt Plugin | Sprout Social
• Supercharging your Gruntfile
• Take Grunt to the Next Level — Jonathan Suh

Grunt: gruntfile.js

// Generated on 2018-03-31 using
// generator-webapp 1.1.2
'use strict';

// # Globbing
// for performance reasons we're only matching one level down:
// 'test/spec/{,*/}*.js'
// If you want to recursively match all subfolders, use:
// 'test/spec/**/*.js'

//export default grunt => {
module.exports = grunt => {

  // Time how long tasks take. Can help when optimizing build times
  require('time-grunt')(grunt);

  // Automatically load required grunt tasks
  require('jit-grunt')(grunt, {
    useminPrepare: 'grunt-usemin'
  });

  // Configurable paths
  const config = {
    app: 'app',
    dist: 'dist'
  };

  // Define the configuration for all the tasks
  grunt.initConfig({

    // Project settings
    config,

    // Watches files for changes and runs tasks based on the changed files
    watch: {
      bower: {
        files: ['bower.json'],
        tasks: ['wiredep']
      },
      babel: {
        files: ['<%= config.app %>/scripts/{,*/}*.js'],
        tasks: ['babel:dist']
      },
      babelTest: {
        files: ['test/spec/{,*/}*.js'],
        tasks: ['babel:test', 'test:watch']
      },
      gruntfile: {
        files: ['Gruntfile.js']
      },
      sass: {
        files: ['<%= config.app %>/styles/{,*/}*.{scss,sass}'],
        tasks: ['sass', 'postcss']
      },
      styles: {
        files: ['<%= config.app %>/styles/{,*/}*.css'],
        tasks: ['newer:copy:styles', 'postcss']
      }
    },

    browserSync: {
      options: {
        notify: false,
        background: true,
        watchOptions: {
          ignored: ''
        }
      },
      livereload: {
        options: {
          files: [
            '<%= config.app %>/{,*/}*.html',
            '.tmp/styles/{,*/}*.css',
            '<%= config.app %>/images/{,*/}*',
            '.tmp/scripts/{,*/}*.js'
          ],
          port: 9000,
          server: {
            baseDir: ['.tmp', config.app],
            routes: {
              '/bower_components': './bower_components'
            }
          }
        }
      },
      test: {
        options: {
          port: 9001,
          open: false,
          logLevel: 'silent',
          host: 'localhost',
          server: {
            baseDir: ['.tmp', './test', config.app],
            routes: {
              '/bower_components': './bower_components'
            }
          }
        }
      },
      dist: {
        options: {
          background: false,
          server: '<%= config.dist %>'
        }
      }
    },

    // Empties folders to start fresh
    clean: {
      dist: {
        files: [{
          dot: true,
          src: [
            '.tmp',
            '<%= config.dist %>/*',
            '!<%= config.dist %>/.git*'
          ]
        }]
      },
      server: '.tmp'
    },

    // Make sure code styles are up to par and there are no obvious mistakes
    eslint: {
      target: [
        'Gruntfile.js',
        '<%= config.app %>/scripts/{,*/}*.js',
        '!<%= config.app %>/scripts/vendor/*',
        'test/spec/{,*/}*.js'
      ]
    },

    // Mocha testing framework configuration options
    mocha: {
      all: {
        options: {
          run: true,
          urls: ['http://<%= browserSync.test.options.host %>:<%= browserSync.test.options.port %>/index.html']
        }
      }
    },

    // Compiles ES6 with Babel
    babel: {
      options: {
        sourceMap: true,
        presets: ['es2015']
      },
      dist: {
        files: [{
          expand: true,
          cwd: '<%= config.app %>/scripts',
          src: '{,*/}*.js',
          dest: '.tmp/scripts',
          ext: '.js'
        }]
      },
      test: {
        files: [{
          expand: true,
          cwd: 'test/spec',
          src: '{,*/}*.js',
          dest: '.tmp/spec',
          ext: '.js'
        }]
      }
    },

    // Compiles Sass to CSS and generates necessary files if requested
    sass: {
      options: {
        sourceMap: true,
        sourceMapEmbed: true,
        sourceMapContents: true,
        includePaths: ['.']
      },
      dist: {
        files: [{
          expand: true,
          cwd: '<%= config.app %>/styles',
          src: ['*.{scss,sass}'],
          dest: '.tmp/styles',
          ext: '.css'
        }]
      }
    },

    postcss: {
      options: {
        map: true,
        processors: [
          // Add vendor prefixed styles
          require('autoprefixer')({
            browsers: ['> 1%', 'last 2 versions', 'Firefox ESR']
          })
        ]
      },
      dist: {
        files: [{
          expand: true,
          cwd: '.tmp/styles/',
          src: '{,*/}*.css',
          dest: '.tmp/styles/'
        }]
      }
    },

    // Automatically inject Bower components into the HTML file
    wiredep: {
      app: {
        src: ['<%= config.app %>/index.html'],
        exclude: ['bootstrap.js'],
        ignorePath: /^(\.\.\/)*\.\./
      },
      sass: {
        src: ['<%= config.app %>/styles/{,*/}*.{scss,sass}'],
        ignorePath: /^(\.\.\/)+/
      }
    },

    // Renames files for browser caching purposes
    filerev: {
      dist: {
        src: [
          '<%= config.dist %>/scripts/{,*/}*.js',
          '<%= config.dist %>/styles/{,*/}*.css',
          '<%= config.dist %>/images/{,*/}*.*',
          '<%= config.dist %>/fonts/{,*/}*.*',
          '<%= config.dist %>/*.{ico,png}'
        ]
      }
    },

    // Reads HTML for usemin blocks to enable smart builds that automatically
    // concat, minify and revision files. Creates configurations in memory so
    // additional tasks can operate on them
    useminPrepare: {
      options: {
        dest: '<%= config.dist %>'
      },
      html: '<%= config.app %>/index.html'
    },

    // Performs rewrites based on rev and the useminPrepare configuration
    usemin: {
      options: {
        assetsDirs: [
          '<%= config.dist %>',
          '<%= config.dist %>/images',
          '<%= config.dist %>/styles'
        ]
      },
      html: ['<%= config.dist %>/{,*/}*.html'],
      css: ['<%= config.dist %>/styles/{,*/}*.css']
    },

    // The following *-min tasks produce minified files in the dist folder
    imagemin: {
      dist: {
        files: [{
          expand: true,
          cwd: '<%= config.app %>/images',
          src: '{,*/}*.{gif,jpeg,jpg,png}',
          dest: '<%= config.dist %>/images'
        },{
          expand: true,
          cwd: '<%= config.app %>',
          src: '*.{ico,png}',
          dest: '<%= config.dist %>'
        }]
      }
    },

    svgmin: {
      dist: {
        files: [{
          expand: true,
          cwd: '<%= config.app %>/images',
          src: '{,*/}*.svg',
          dest: '<%= config.dist %>/images'
        }]
      }
    },

    htmlmin: {
      dist: {
        options: {
          collapseBooleanAttributes: true,
          collapseWhitespace: true,
          conservativeCollapse: true,
          removeAttributeQuotes: true,
          removeCommentsFromCDATA: true,
          removeEmptyAttributes: true,
          removeOptionalTags: true,
          // true would impact styles with attribute selectors
          removeRedundantAttributes: false,
          useShortDoctype: true
        },
        files: [{
          expand: true,
          cwd: '<%= config.dist %>',
          src: '{,*/}*.html',
          dest: '<%= config.dist %>'
        }]
      }
    },

    // By default, your `index.html`'s <!-- Usemin block --> will take care
    // of minification. These next options are pre-configured if you do not
    // wish to use the Usemin blocks.
    // cssmin: {
    //   dist: {
    //     files: {
    //       '<%= config.dist %>/styles/main.css': [
    //         '.tmp/styles/{,*/}*.css',
    //         '<%= config.app %>/styles/{,*/}*.css'
    //       ]
    //     }
    //   }
    // },
    // uglify: {
    //   dist: {
    //     files: {
    //       '<%= config.dist %>/scripts/scripts.js': [
    //         '<%= config.dist %>/scripts/scripts.js'
    //       ]
    //     }
    //   }
    // },
    // concat: {
    //   dist: {}
    // },

    // Copies remaining files to places other tasks can use
    copy: {
      dist: {
        files: [{
          expand: true,
          dot: true,
          cwd: '<%= config.app %>',
          dest: '<%= config.dist %>',
          src: [
            '*.txt',
            'images/{,*/}*.webp',
            '{,*/}*.html',
            'fonts/{,*/}*.*'
          ]
        }, {
          expand: true,
          dot: true,
          cwd: '.',
          src: 'bower_components/bootstrap-sass/assets/fonts/bootstrap/*',
          dest: '<%= config.dist %>'
        }]
      }
    },

    // Generates a custom Modernizr build that includes only the tests you
    // reference in your app
    modernizr: {
      dist: {
        devFile: 'bower_components/modernizr/modernizr.js',
        outputFile: '<%= config.dist %>/scripts/vendor/modernizr.js',
        files: {
          src: [
            '<%= config.dist %>/scripts/{,*/}*.js',
            '<%= config.dist %>/styles/{,*/}*.css',
            '!<%= config.dist %>/scripts/vendor/*'
          ]
        },
        uglify: true
      }
    },

    // Run some tasks in parallel to speed up build process
    concurrent: {
      server: [
        'babel:dist',
        'sass'
      ],
      test: [
        'babel'
      ],
      dist: [
        'babel',
        'sass',
        'imagemin',
        'svgmin'
      ]
    }
  });


  grunt.registerTask('serve', 'start the server and preview your app', target => {

    if (target === 'dist') {
      return grunt.task.run(['build', 'browserSync:dist']);
    }

    grunt.task.run([
      'clean:server',
      'wiredep',
      'concurrent:server',
      'postcss',
      'browserSync:livereload',
      'watch'
    ]);
  });

  grunt.registerTask('server', target => {
    grunt.log.warn('The `server` task has been deprecated. Use `grunt serve` to start a server.');
    grunt.task.run([target ? (`serve:${target}`) : 'serve']);
  });

  grunt.registerTask('test', target => {
    if (target !== 'watch') {
      grunt.task.run([
        'clean:server',
        'concurrent:test',
        'postcss'
      ]);
    }

    grunt.task.run([
      'browserSync:test',
      'mocha'
    ]);
  });

  grunt.registerTask('build', [
    'clean:dist',
    'wiredep',
    'useminPrepare',
    'concurrent:dist',
    'postcss',
    'concat',
    'cssmin',
    'uglify',
    'copy:dist',
    'modernizr',
    'filerev',
    'usemin',
    'htmlmin'
  ]);

  grunt.registerTask('default', [
    'newer:eslint',
    'test',
    'build'
  ]);
};

Gulp

Caractísticas

• Filosofía de código sobre configuración
• Basado en stream
• No es necesario usar archivos temporales
• Claridad en creación de tareas y seguimiento de procesos
• Gran cantidad de Plugins
• Cuenta con una comunidad sólida y madura
• El sistema de streams y Promisesno es sencillo para developers juniors

Instalación

• Instalamos Gulp global

npm install --global gulp

• Incluimos la dependencia en package.json

npm install --save-dev gulp

Tareas por defecto

• Creamos gulpfile.js y agregamos dependencias y la primera tarea por defecto
• Definición

//import gulp from 'gulp';
const gulp = require('gulp');

gulp.task('default', () => {
  console.log("Estas en la tarea por defecto!")
});

• Lanzamiento

gulp

Más tareas

• Creamos una tarea nueva para gestionar la concatenación y minificación de los archivos js.
• Definición

/*
import gulp from 'gulp';
import concat from 'gulp-concat';
import uglify from 'gulp-uglify';
*/
const gulp = require('gulp'),
  concat = require('gulp-concat'),
  uglify = require('gulp-uglify');

gulp.task('concat-ugly', () => {
  console.log("Estas en la tarea de concatenación!")  
  gulp.src('js/sources/*.js')
  .pipe(concat('app.min.js'))
  .pipe(uglify())
  .pipe(gulp.dest('dist/js'))
});

• Instalamos las nuevas dependencias

npm install -save gulp-concat && npm install -save gulp-uglify

• Lanzamiento

gulp concat-ugly

Agrupando tareas

• Definición

gulp.task('distro-lista', ['imagenes', 'css', 'js']);

• Lanzamiento

gulp distro-lista

Concatenando tareas

• Definición

gulp.task('css-paso-2', ['css-paso-1'], () => {
  console.log("css-paso-2 empieza solo cuando... css-paso-1 haya termiando!")
});

• Lanzamiento

gulp css-paso-2

Ejemplo de gulpfile.js

Entendiendo Gulp gulp.src() y gulp.dest()

• Un solo archivo

gulp.src('client/templates/index.jade')
// .pipe(...)

• Múltiples archivos

gulp.src(['client/*.js', '!client/b*.js', 'client/bad.js'])
// .pipe(...)

• Múltiples archivos y carpetas

gulp.src('client/templates/**/*.jade')
// .pipe(...)

• Exclusión

!js/secreto-config.js

• Especificando la extensión

publico/*.+(js|css)

• Más opciones

gulp.watch()

• Monitoriza de manera activa uno o varios archivos y dispara tareas específicas cuando se hayan modificado

gulp.watch('js/source/*.js', ['js']);

Gulp: Plugins

• gulp-debug: BÁSICO para debugear las tareas de GULP y los ficheros en scope de la tarea
• gulp-concat: Concatenación de archivos
• gulp-uglify: Comprime javascript usando UglifyJS2
• gulp-stylus: Compilar de .styl a .css
• gulp-coffee: Compilar de .coffee a .js
• gulp-jade: Compilador de .jade a .html
• gulp-if: Control adiccional para el flujo de subtareas
• gulp-imagemin: Minificación de imágenes con formato .png, .jpeg, .gif y .svg, más opciones
• gulp-jshint: JSHint
• gulp.spritesmith: Crea Sprites y el css adiccional en diversos formatos (.css, .json, Sass, Less)
• gulp-zip: Compresor ZIP
• gulp-csslint: CSS Linter
• gulp-eslint: ESLint
• gulp-gh-pages: Gestiona la publicación en GitHub Pages
• gulp-git: Gestiona Git desde Gulp
• gulp-htmlmin: Minificador de HTML
• gulp-iconfont: Creando fuentes de Iconos desde archivos vectoriales
• gulp-jsonlint: Linter para json
• gulp-markdown: Markdown a HTML
• gulp-sourcemaps: Crea SourceMaps
• gulp-uncss: Elimina CSS que no se use
• gulp-jsdoc-to-markdown: Conversor de jsdocs a markdown
• gulp-unzip: Descompresor ZIP
• gulp-webstandards: Verifica prefijos CSS, Versión de librerías js, dcoType, compatibildiad entre navegadores, etc...
• gulp-filesize: Muestra el tamaño de los archivos.
• gulp-grunt: Tareas de Grutn funcionan en Gulp
• gulp-shell: Manejando comandos de terminal

Interesante de integrar en los proyectos:

• Easy Accessibility Testing with aXe
• puppeteer: Headless Chrome Node API
• pageres: Genera pantallazos de la web en diversos tamaños
• PSI: PageSpeed Insights desde la terminal
• Lighthouse: Auditing, performance metrics, and best practices for Progressive Web Apps

Gulp: gulpfile.js

// generated on 2018-03-31 using generator-webapp 3.0.1
const gulp = require('gulp');
const gulpLoadPlugins = require('gulp-load-plugins');
const browserSync = require('browser-sync').create();
const del = require('del');
const wiredep = require('wiredep').stream;
const runSequence = require('run-sequence');

const $ = gulpLoadPlugins();
const reload = browserSync.reload;

let dev = true;

gulp.task('styles', () => {
  return gulp.src('app/styles/*.scss')
    .pipe($.plumber())
    .pipe($.if(dev, $.sourcemaps.init()))
    .pipe($.sass.sync({
      outputStyle: 'expanded',
      precision: 10,
      includePaths: ['.']
    }).on('error', $.sass.logError))
    .pipe($.autoprefixer({browsers: ['> 1%', 'last 2 versions', 'Firefox ESR']}))
    .pipe($.if(dev, $.sourcemaps.write()))
    .pipe(gulp.dest('.tmp/styles'))
    .pipe(reload({stream: true}));
});

gulp.task('scripts', () => {
  return gulp.src('app/scripts/**/*.js')
    .pipe($.plumber())
    .pipe($.if(dev, $.sourcemaps.init()))
    .pipe($.babel())
    .pipe($.if(dev, $.sourcemaps.write('.')))
    .pipe(gulp.dest('.tmp/scripts'))
    .pipe(reload({stream: true}));
});

function lint(files) {
  return gulp.src(files)
    .pipe($.eslint({ fix: true }))
    .pipe(reload({stream: true, once: true}))
    .pipe($.eslint.format())
    .pipe($.if(!browserSync.active, $.eslint.failAfterError()));
}

gulp.task('lint', () => {
  return lint('app/scripts/**/*.js')
    .pipe(gulp.dest('app/scripts'));
});
gulp.task('lint:test', () => {
  return lint('test/spec/**/*.js')
    .pipe(gulp.dest('test/spec'));
});

gulp.task('html', ['styles', 'scripts'], () => {
  return gulp.src('app/*.html')
    .pipe($.useref({searchPath: ['.tmp', 'app', '.']}))
    .pipe($.if(/\.js$/, $.uglify({compress: {drop_console: true}})))
    .pipe($.if(/\.css$/, $.cssnano({safe: true, autoprefixer: false})))
    .pipe($.if(/\.html$/, $.htmlmin({
      collapseWhitespace: true,
      minifyCSS: true,
      minifyJS: {compress: {drop_console: true}},
      processConditionalComments: true,
      removeComments: true,
      removeEmptyAttributes: true,
      removeScriptTypeAttributes: true,
      removeStyleLinkTypeAttributes: true
    })))
    .pipe(gulp.dest('dist'));
});

gulp.task('images', () => {
  return gulp.src('app/images/**/*')
    .pipe($.cache($.imagemin()))
    .pipe(gulp.dest('dist/images'));
});

gulp.task('fonts', () => {
  return gulp.src(require('main-bower-files')('**/*.{eot,svg,ttf,woff,woff2}', function (err) {})
    .concat('app/fonts/**/*'))
    .pipe($.if(dev, gulp.dest('.tmp/fonts'), gulp.dest('dist/fonts')));
});

gulp.task('extras', () => {
  return gulp.src([
    'app/*',
    '!app/*.html'
  ], {
    dot: true
  }).pipe(gulp.dest('dist'));
});

gulp.task('clean', del.bind(null, ['.tmp', 'dist']));

gulp.task('serve', () => {
  runSequence(['clean', 'wiredep'], ['styles', 'scripts', 'fonts'], () => {
    browserSync.init({
      notify: false,
      port: 9000,
      server: {
        baseDir: ['.tmp', 'app'],
        routes: {
          '/bower_components': 'bower_components'
        }
      }
    });

    gulp.watch([
      'app/*.html',
      'app/images/**/*',
      '.tmp/fonts/**/*'
    ]).on('change', reload);

    gulp.watch('app/styles/**/*.scss', ['styles']);
    gulp.watch('app/scripts/**/*.js', ['scripts']);
    gulp.watch('app/fonts/**/*', ['fonts']);
    gulp.watch('bower.json', ['wiredep', 'fonts']);
  });
});

gulp.task('serve:dist', ['default'], () => {
  browserSync.init({
    notify: false,
    port: 9000,
    server: {
      baseDir: ['dist']
    }
  });
});

gulp.task('serve:test', ['scripts'], () => {
  browserSync.init({
    notify: false,
    port: 9000,
    ui: false,
    server: {
      baseDir: 'test',
      routes: {
        '/scripts': '.tmp/scripts',
        '/bower_components': 'bower_components'
      }
    }
  });

  gulp.watch('app/scripts/**/*.js', ['scripts']);
  gulp.watch(['test/spec/**/*.js', 'test/index.html']).on('change', reload);
  gulp.watch('test/spec/**/*.js', ['lint:test']);
});

// inject bower components
gulp.task('wiredep', () => {
  gulp.src('app/styles/*.scss')
    .pipe($.filter(file => file.stat && file.stat.size))
    .pipe(wiredep({
      ignorePath: /^(\.\.\/)+/
    }))
    .pipe(gulp.dest('app/styles'));

  gulp.src('app/*.html')
    .pipe(wiredep({
      exclude: ['bootstrap-sass'],
      ignorePath: /^(\.\.\/)*\.\./
    }))
    .pipe(gulp.dest('app'));
});

gulp.task('build', ['lint', 'html', 'images', 'fonts', 'extras'], () => {
  return gulp.src('dist/**/*').pipe($.size({title: 'build', gzip: true}));
});

gulp.task('default', () => {
  return new Promise(resolve => {
    dev = false;
    runSequence(['clean', 'wiredep'], 'build', resolve);
  });
});

Gulp 4

Gulp 4: Cambios

• Nuevo sistema de dependencias gulp.task() solo admite 2 argumentos
• gulp.series() y 'gulp.parallel()' son ahora nativas. ¡Adios runSequence!.
• El orden de las tareas es clave y ya no podemos organizarlas como queramos, deben ir por orden de carga
• Es necesario terminar cada tarea con un callback o resolver la promesa. En Gulp3 no era necesario.
• Por el momento tiene poca adopción

Si tienes un gulpile.js funcionando con Gulp 3.x, no merece la pena migrarse.

Nuevo sistema de dependencias en detalles

Antes - Gulp 3.9.x

gulp.task('a', function () {
  // Do something.
});
gulp.task('b', ['a'], function () {
  // Do some stuff.
});

gulp.task('c', ['b'], function () {
    // Do some more stuff.
});

Ahora - Gulp 4.x

• Las tareas solo tienen 2 argumentos.
• La concatenación de tareas puede ser serializada con gulp.series() o paralelizada con 'gulp.parallel()'

gulp.task('my-tasks', gulp.series('a', 'b', 'c', function() {
  // Do something after a, b, and c are finished.
}));

gulp.task('build', gulp.parallel('styles', 'scripts', 'images', function () {
  // Build the website.
}));

Gulp 4: Guías

• The Complete-Ish Guide to Upgrading to Gulp 4
• Web Tooling and Automatisation using gulp 4
• How to install Gulp 4 before it's officially released
• Migrating to gulp 4 by example
• How to Upgrade to Gulp 4
• Getting started with Gulp 4 for Angular
• A quick guide for switching to gulp 4

Gulp 4: Ejemplo

/*
import gulp from 'gulp';
import less from 'gulp-less';
import babel from 'gulp-babel';
import concat from 'gulp-concat';
import uglify from 'gulp-uglify';
import rename from 'gulp-rename';
import cleanCSS from 'gulp-clean-css';
import del from 'del';
*/

const gulp = require('gulp'),
  less = require('gulp-less'),
  babel = require('gulp-babel'),
  concat = require('gulp-concat'),
  uglify = require('gulp-uglify'),
  rename = require('gulp-rename'),
  cleanCSS = require('gulp-clean-css'),
  del = require('del');

const paths = {
  styles: {
    src: 'src/styles/**/*.less',
    dest: 'assets/styles/'
  },
  scripts: {
    src: 'src/scripts/**/*.js',
    dest: 'assets/scripts/'
  }
};

/* Not all tasks need to use streams, a gulpfile is just another node program
 * and you can use all packages available on npm, but it must return either a
 * Promise, a Stream or take a callback and call it
 */
function clean() {
  // You can use multiple globbing patterns as you would with `gulp.src`,
  // for example if you are using del 2.0 or above, return its promise
  return del([ 'assets' ]);
}

/*
 * Define our tasks using plain functions
 */
function styles() {
  return gulp.src(paths.styles.src)
    .pipe(less())
    .pipe(cleanCSS())
    // pass in options to the stream
    .pipe(rename({
      basename: 'main',
      suffix: '.min'
    }))
    .pipe(gulp.dest(paths.styles.dest));
}

function scripts() {
  return gulp.src(paths.scripts.src, { sourcemaps: true })
    .pipe(babel())
    .pipe(uglify())
    .pipe(concat('main.min.js'))
    .pipe(gulp.dest(paths.scripts.dest));
}

function watch() {
  gulp.watch(paths.scripts.src, scripts);
  gulp.watch(paths.styles.src, styles);
}

// You can use CommonJS `exports` module notation to declare tasks
/*
export {clean};
export {styles};
export {scripts};
export {watch};
*/
exports.clean = clean;
exports.styles = styles;
exports.scripts = scripts;
exports.watch = watch;

// Specify if tasks run in series or parallel using `gulp.series` and `gulp.parallel`
const build = gulp.series(clean, gulp.parallel(styles, scripts));

// You can still use `gulp.task` to expose tasks
gulp.task('build', build);

// Define default task that can be called by just running `gulp` from cli
gulp.task('default', build);

Grunt vs. Gulp

Grunt:

Gulp: