Merge pull request #1 from aphuong/master

Update app.js
Merge pull request #2 from aphuong/master

Update app.js
Merge pull request #3 from aphuong/master

Update app.js
Update app.js
Update app.js
Update app.js
Update app.js
Update app.js
Update app.js
Update app.js
Update app.js
Update app.js
Merge pull request #4 from aphuong/gh-pages

update javascript