@function can.stache.helpers.joinBase {{joinBase args}}
@parent can.stache.htags 16

@signature `{{joinBase expr}}`

Return an application-relative url for a resource.

@param {can.stache.expression} [expr...] An expression or key that references a value within the current or parent scope.

@return {String} An application-relative url.

@body

The `joinBase` helper is used to create urls within your application for static resources, such as images. An example usage:

    {{joinBase "hello/" name ".png"}}

Where `name` is a scope value, this might return `http://example.com/app/hello/world.png` if the application is `http://example.com/app`.

The url to join with is determined by the following factors:

* If attempting to load a relative url, such as `{{joinBase "../foo.png"}}` and using StealJS the template's address will be used as a reference to look up the location.
* If the `can.baseURL` string is set, this will be used.
* If the `System.baseURL` is set, this will be used.
* Lastly we fall back to `location.pathname`.