Though there are tons of PLUGINS which you can use, but below are the most used.

• watch: RUN predefined tasks whenever watched file PATTERNS are added, changed or deleted.
• jshint: Validate files with JSHint
• uglify: Minify files with UglifyJS
• concat: Concatenate files.
• cssmin: Minify CSS
• less: Compile LESS files to CSS.

Below is a sample gruntfile.JS for your reference.

1. module.exports = function(grunt) {
2. grunt.initConfig({
3. pkg: grunt.file.readJSON('package.json'),
4. concat: {
5. options: {
6. separator: ';'
7. },
8. dist: {
9. src: ['src/**/*.js'],
10. dest: 'dist/<%= pkg.name %>.js'
11. }
12. },
13. uglify: {
14. options: {
15. BANNER: '/*! <%= pkg.name %> <%= grunt.template.today("dd-mm-yyyy") %> */n'
16. },
17. dist: {
18. files: {
19. 'dist/<%= pkg.name %>.min.js': ['<%= concat.dist.dest %>']
20. }
21. }
22. },
23. jshint: {
24. files: ['Gruntfile.js', 'src/**/*.js', 'test/**/*.js'],
25. options: {
26. // options here to override JSHint defaults
27. globals: {
28. jQuery: true,
29. console: true,
30. module: true,
31. document: true
32. }
33. }
34. }
35. });
36. grunt.loadNpmTasks('grunt-contrib-uglify');
37. grunt.loadNpmTasks('grunt-contrib-jshint');
38. grunt.loadNpmTasks('grunt-contrib-concat');
39. grunt.registerTask('test', ['jshint']);
40. grunt.registerTask('default', ['jshint', 'concat', 'uglify']);
41. };

Though there are tons of plugins which you can use, but below are the most used.

Below is a sample gruntfile.js for your reference.