When you start watch, it says waiting for a long time after the grunt command, what's the matter?

Question

Node.js

Good afternoon, I'm new to grunt. When I execute the grunt command, the process hangs for a long time:

Running "concat:dist" (concat) task

Running "uglify:build" (uglify) task
File assets/js/production.min.js created: 69.55 kB → 60.28 kB
>> 1 file created.

Running "watch" task
Waiting...

Here is the gruntfile.js file:

module.exports = function(grunt) {

    // 1. Вся настройка находится здесь
    grunt.initConfig({
        pkg: grunt.file.readJSON('package.json'),

        concat: {
            dist: {
                src: [
                    'assets/js/libs/*.js',
                    'assets/js/vendor/*.js',
                    'assets/js/parts/*.js'
                ],
                dest: 'assets/js/production.js'
            }
        },
        uglify: {
            build: {
                src: 'assets/js/production.js',
                dest: 'assets/js/production.min.js'
            }
        },
        watch: {
            scripts: {
                files: [
                    'assets/js/*.js',
                    'assets/css/production.css'
                ],
                tasks: ['concat', 'uglify'],
                options: {
                    spawn: false
                },
            }
        },
        imagemin: {
            dynamic: {
                files: [{
                    expand: true,
                    cwd: 'assets/images/',
                    src: ['**/*.{png,jpg,gif}'],
                    dest: 'assets/images/build/'
                }]
            }
        },
        less: {
            development: {
                options: {
                    paths: ["assets/css"],
                    compress: true
                },
                files: {
                    "assets/css/production.css": "assets/css/production.less"
                }
            }
        },
        autoprefixer: {
            options: {
                browsers: ['last 2 versions', 'ie 9']
            },
            your_target: {
                src: 'assets/css/production.css',
                dest: 'assets/css/production.css'
            }
        }
    });

    // 3. Тут мы указываем Grunt, что хотим использовать этот плагин
    grunt.loadNpmTasks('grunt-contrib-concat');
    grunt.loadNpmTasks('grunt-contrib-uglify');
    grunt.loadNpmTasks('grunt-contrib-watch');
    grunt.loadNpmTasks('grunt-contrib-imagemin');
    grunt.loadNpmTasks('grunt-contrib-less');
    grunt.loadNpmTasks('grunt-autoprefixer');
    
    // 4. Указываем, какие задачи выполняются, когда мы вводим «grunt» в терминале
    grunt.registerTask('default', ['concat', 'uglify', 'watch', 'imagemin', 'less', 'autoprefixer']);
};

Answer 1

watch waits for file changes

files: [
    'assets/js/*.js',
    'assets/css/production.css'
],

in order to perform tasks when they change,
this is often used to rebuild the project "in real time" and see the result