This Google video confirms again that Google can search Javascript sites and provides excellent SEO advice:
I believe the question now is not if Google can or cannot. We already know that Google can.
The question now is about “when” and what percentage of your site will google do it.
Meteor apps are single page apps (SPA). But google does not know it (yet). Instead of a few kilobytes of html, meteor apps include hundreds of kilobytes or sometimes a few megabytes of javascripts. Those are heavy javascripts that google has to load, read, and execute on every page. That can quickly get very expensive compared to a miniscule html. So unless Google learns how to properly crawl an SPA, don’t expect meteor apps to be crawled efficiently as javascript.
Due to this, the first thing that google will crawl (and index) will be the html results. And it will schedule “if and when” to execute the javascript. And that gap of crawling and execution can take days which can result to cases when the downloaded js is no longer compatible with the server-side app if you happen to update your app.