To access the term store with JavaScript, refer to the following links:

https://cann0nf0dder.wordpress.com/2013/04/09/accessing-taxonomy-term-store-with-jsom/
http://dotnetmafia.sys-con.com/node/2639264/mobile

https://habaneroconsulting.com/insights/returning-a-sharepoint-2013-termset-in-a-tree-structure-using-javascript#.V4GMso-cG70

http://sharepoint.stackexchange.com/questions/78514/accessing-terms-in-term-store-using-jsom-in-sharepoint-2013

http://www.vrdmn.com/2012/12/working-with-taxonomy-and-javascript-in.html