Configure few task on Gruntfile.js

Gruntfile.js

    // configure jshint to validate all js files -----------------------------------
    jshint: {
      options: {
        reporter: require('jshint-stylish') // use jshint-stylish to make our errors look and read good
      },

      // when this task is run, lint the Gruntfile and all js files in src
      build: ['src/js/*.js']
    }

    // configure uglify to minify single js file
    uglify: {
      options: {
        banner: '/*\n <%= pkg.name %> <%= grunt.template.today("yyyy-mm-dd") %> \n*/\n'
      },
      build: {
        files: {
          'dist/js/magic.min.js': 'src/js/magic.js'
        }
      }
    }
    
    //Minify multiple js files in to one file
    uglify: {
      options: {
        banner: '/*\n <%= pkg.name %> <%= grunt.template.today("yyyy-mm-dd") %> \n*/\n'
      },
      build: {
		src : 'src/js/*.js',
		dest : 'dest/js/build.js'
	  }
    }
    
    //Minify multiple js files separately
	uglify: {
		files: { 
            src: 'src/js/*.js',  // source files mask
            dest: 'dest/js/',    // destination folder
            expand: true,    // allow dynamic building
            flatten: true,   // remove all unnecessary nesting
            ext: '.min.js'   // replace .js to .min.js
        }
    }    
    
    
	//Concat files
	concat: {
	  options: {
		  // define a string to put between each file in the concatenated output
		  separator: ';'
	  },
	  dist: {
		  src: ['src/**/*.js'],		  // the files to concatenate
		dest: 'dist/<%= pkg.name %>.js'		  // the location of the resulting JS file
	  }
	}
	

	
	//Minimize images
	imagemin: {
	   dist: {
	      options: {
	        optimizationLevel: 5
	      },
	      files: [{
	         expand: true,
	         cwd: 'src/img/images',
	         src: ['**/*.{png,jpg,gif}'],
	         dest: 'dist/img/'
	      }]
	   }
	}
	
	
	
	//Remove unused css selectors from stylesheet.
	//ignore : specify a list of selectors that should not be removed
	//ignoreSheets : that allows us to specify style sheets to ignore
	uncss: {
	   dist: {
	      options: {
	         ignore: [/js-.+/, '.special-class'],
	         ignoreSheets: [/fonts.googleapis/],
	      },
	      files: {
	         'dist/css/unused-removed.css': ['src/index.html', 'src/contact.html', 'src/service.html']
	      }
	   }
	}	
	
	
	//Minify HTML
	//process all the pages placed in the “src” directory and its subfolders.
	//For each of these pages, the task removes all the comments and collapses the spaces it finds.
	//store the results in the “dist” directory
	htmlmin: {
	   dist: {
	      options: {
	         removeComments: true,
	         collapseWhitespace: true
	      },
	      files: [{
	         expand: true,
	         cwd: 'src',
	         src: '**/*.html',
	         dest: 'dist/'
	      }]
	   }
	}