You can use Grunt also :
For Grunt, follow these steps :
Step 1: install node.js from http://nodejs.org/
Step 2: open window command prompt as admin and then run command
npm install -g grunt-cli
(this command will set grunt in system path to run grunt globally, then we can run grunt from any directory)
Step 3: Create package.json and Gruntfile.js in root of portal project where you want to setup grunt.
Step 4: Now go in project directory from command prompt then run command
npm install -g grunt-init
(this command will create node_modules folder in project where all plugin will store)
Step 5: install packages or plugin
npm install grunt --save-dev
npm install grunt-contrib-clean --save-dev
npm install grunt-contrib-copy --save-dev
npm install grunt-contrib-concat --save-dev
npm install grunt-contrib-cssmin --save-dev
npm install grunt-contrib-uglify --save-dev
npm install grunt-usemin --save-dev
npm install grunt-contrib-watch –save-dev
Step 6: open index file of project in VS where we have setup grunt.
Place all script with in below tag
// all script here
Step 7: Run grunt in cmd
Command: grunt
Step 8: after run grunt all file will be merge in a single file in dist/js/build.js
Step 9: Now give reference only build.js in index file and remove all other script reference from index file.