CakePHP Js::bufferメソッドを使う前提であれば、Js::setで値をJSへ渡すことが可能

default.ctp

<?php
// in layout/default.ctp
?>
<!-- // .. snip -->

<?php echo $this->Js->writeBuffer(); ?>

</body></html>

some_view.ctp

<?php
// some_view.ctp

// set to app.webroot
$this->Js->set('webroot', $this->Html->url('/'));
// set to app.here
$this->Js->set('here', $this->Html->url());

// call
$this->Js->buffer("
  console.log(app.webroot);
  console.log(app.here);
");