concat.js is being included in the concat task's source files public/js/*.js. You could have a task that removes concat.js (if the file exists) before concatenating again, pass an array to explicitly define which files you want to concatenate and their order, or change the structure of your project.
If doing the latter, you could put all your sources under ./src and your built files under ./dest
src
+-- css
¦ +-- 1.css
¦ +-- 2.css
¦ +-- 3.css
+-- js
+-- 1.js
+-- 2.js
+-- 3.js
Then set up your concat task
concat: {
js: {
src: 'src/js/*.js',
dest: 'dest/js/concat.js'
},
css: {
src: 'src/css/*.css',
dest: 'dest/css/concat.css'
}
},
Your min task
min: {
js: {
src: 'dest/js/concat.js',
dest: 'dest/js/concat.min.js'
}
},
The build-in min task uses UglifyJS, so you need a replacement. I found grunt-css to be pretty good. After installing it, load it into your grunt file
grunt.loadNpmTasks('grunt-css');
And then set it up
cssmin: {
css:{
src: 'dest/css/concat.css',
dest: 'dest/css/concat.min.css'
}
}
Notice that the usage is similar to the built-in min.
Change your default task to
grunt.registerTask('default', 'concat min cssmin');
Now, running grunt will produce the results you want.
dest
+-- css
¦ +-- concat.css
¦ +-- concat.min.css
+-- js
+-- concat.js
+-- concat.min.js