Grunt Setup with LESS

Gruntfile.js

'use strict';
module.exports = function(grunt) {

    // load all grunt tasks matching the `grunt-*` pattern
    require('load-grunt-tasks')(grunt);

    grunt.initConfig({

        // watch for changes and trigger compass, jshint, uglify and livereload
        watch: {
            less: {
                files: ['assets/less/**/*.less'],
                tasks: ['less:development']
            },
            js: {
                files: '<%= jshint.all %>',
                tasks: ['jshint', 'uglify']
            },
            livereload: {
                options: { livereload: true },
                files: ['style.css', 'assets/js/*.js', '*.html', '*.php', 'assets/images/**/*.{png,jpg,jpeg,gif,webp,svg}']
            }
        },

        // less
      less: {
        development: {
          options: {
            paths: ["assets/css"]
          },
          files: {
            "path/to/result.css": "path/to/source.less"
          }
        },
        production: {
          options: {
            paths: ["assets/css"],
            yuicompress: true
          },
          files: {
            "path/to/result.css": "path/to/source.less"
          }
        }
      }

        // javascript linting with jshint
        jshint: {
            options: {
                jshintrc: '.jshintrc',
                "force": true
            },
            all: [
                'Gruntfile.js',
                'assets/js/source/**/*.js'
            ]
        },

        // uglify to concat, minify, and make source maps
        uglify: {
            plugins: {
                options: {
                    sourceMap: 'assets/js/plugins.js.map',
                    sourceMappingURL: 'plugins.js.map',
                    sourceMapPrefix: 2
                },
                files: {
                    'assets/js/plugins.min.js': [
                        'assets/js/source/plugins.js',
                        // 'assets/js/vendor/yourplugin/yourplugin.js',
                    ]
                }
            },
            main: {
                options: {
                    sourceMap: 'assets/js/main.js.map',
                    sourceMappingURL: 'main.js.map',
                    sourceMapPrefix: 2
                },
                files: {
                    'assets/js/main.min.js': [
                        'assets/js/source/main.js'
                    ]
                }
            }
        },

        // image optimization
        imagemin: {
            dist: {
                options: {
                    optimizationLevel: 7,
                    progressive: true
                },
                files: [{
                    expand: true,
                    cwd: 'assets/images/',
                    src: '**/*',
                    dest: 'assets/images/'
                }]
            }
        },

    });

    // register task
    grunt.registerTask('default', ['watch']);
    grunt.resisterTask('build', 'less:production')

};

package.json

{
  "name": "wordpress-starter-theme",
  "version": "1.0.0",
  "dependencies": {
    "load-grunt-tasks": "~0.1.0"
  },
  "devDependencies": {
    "grunt": "~0.4.1",
    "grunt-contrib-less": "~0.7.0",
    "grunt-contrib-jshint": "~0.6.4",
    "grunt-contrib-uglify": "~0.2.4",
    "grunt-contrib-watch": "~0.5.3"
  }
}