Grunt - Sample File

In this chapter, let us create a simple Grunt file using the following plugins −

  • grunt-contrib-uglify
  • grunt-contrib-concat
  • grunt-contrib-jshint
  • grunt-contrib-watch

Install all the above plugins and follow the steps given below to create a simple Gruntfile.js −

Step 1 − You need to create a wrapper function, which encapsulates the configurations for your Grunt.

module.exports = function(grunt) {};

Step 2 − Initialize your configuration object as shown below −

grunt.initConfig({});

Step 3 − Next, read the project settings from the package.json file into the pkg property. It enables us to refer to the properties values within yourpackage.json file.

pkg: grunt.file.readJSON('package.json')

Step 4 − Next, you can define configurations for tasks. Let us create our first task concat to concatenate all the files that are present in the src/ folder and store the concatenated .js file under the dist/ folder.

concat: {
   options: {
      // define a string to insert between files in the concatenated output
      separator: ';'
   },
   dist: {
      // files needs to be concatenated
      src: ['src/**/*.js'],
      // location of the concatenated output JS file
      dest: 'dist/<%= pkg.name %>.js'
   }
}

Step 5 − Now, let us create another task called uglify to minify our JavaScript.

uglify: {
   options: {
      // banner will be inserted at the top of the output which displays the date and time
      banner: '/*! <%= pkg.name %> <%= grunt.template.today() %> */\n'
   },
   dist: {
      files: {
         'dist/<%= pkg.name %>.min.js': ['<%= concat.dist.dest %>']
      }
   }
}

The above task creates a file within the dist/ folder which contains the minified .js files. The <%= concat.dist.dest %> will instruct uglify to minify the file that concat task generates.

Step 6 − Let us configure JSHint plugin by creating jshint task.

jshint: {
   // define the files to lint
   files: ['Gruntfile.js', 'src/**/*.js'],
   // configure JSHint
   options: {
      // more options here if you want to override JSHint defaults
      globals: {
         jQuery: true,
      }
   }
}

The above jshint task accepts an array of files and then an object of options. The above task will look for any coding violation in Gruntfile.js and src/**/*.js files.

Step 7 − Next, we have the watch task which looks for changes in any of the specified files and runs the tasks you specify.

watch: {
   files: ['<%= jshint.files %>'],
   tasks: ['jshint']
}

Step 8 − Next, we have to load Grunt plugins which have all been installed via _npm.

grunt.loadNpmTasks('grunt-contrib-uglify');

grunt.loadNpmTasks('grunt-contrib-jshint');

grunt.loadNpmTasks('grunt-contrib-watch');

grunt.loadNpmTasks('grunt-contrib-concat');

Step 9 − Finally, we have to define the default task.

grunt.registerTask('default', ['jshint', 'concat', 'uglify']);

The default task can be run by just typing the grunt command on command line.

Here is your complete Gruntfile.js −

module.exports = function(grunt) {

   grunt.initConfig({
      pkg: grunt.file.readJSON('package.json'),
      concat: {
         options: {
            separator: ';'
         },
         dist: {
            src: ['src/**/*.js'],
            dest: 'dist/<%= pkg.name %>.js'
         }
      },
      uglify: {
         options: {
            banner: '/*! <%= pkg.name %> <%= grunt.template.today() %> */\n'
         },
         dist: {
            files: {
               'dist/<%= pkg.name %>.min.js': ['<%= concat.dist.dest %>']
            }
         }
      },
      jshint: {
         // define the files to lint
         files: ['Gruntfile.js', 'src/**/*.js'],
         // configure JSHint
         options: {
            // more options here if you want to override JSHint defaults
            globals: {
               jQuery: true,
            }
         }
      },
      watch: {
         files: ['<%= jshint.files %>'],
         tasks: ['jshint']
      }
   });

   grunt.loadNpmTasks('grunt-contrib-uglify');
   grunt.loadNpmTasks('grunt-contrib-jshint');
   grunt.loadNpmTasks('grunt-contrib-watch');
   grunt.loadNpmTasks('grunt-contrib-concat');

   grunt.registerTask('default', ['jshint', 'concat', 'uglify']);

};
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