Using GitLab Variables in a vanilla HTML page with JavaScript -

gitlab supports predefined environment variables, yaml-defined variables, , secure user variables - http://doc.gitlab.com/ce/ci/variables/readme.html

how can use secure user variable part of javascript script within basic gitlab-pages site? (i.e. site isn't using ruby, node, etc., using html, css, & javascript)

for example, have start_page_user , start_page_id variables defined project. .gitlab-ci.yml exposes them via echo $start_page_user & echo $start_page_id, , have verified exposed in build log. how can use variables in javascript (e.g. setting username in config.js):

var config = {   user: typeof $start_page_user !== 'undefined' ? start_page_user : "example user" }; 

project variables testing enviroment. not code! cannot access variables in code.

as documentation said:

when receiving build gitlab ci, runner prepares build environment. starts setting list of predefined variables (environment variables) , list of user-defined variables