Ruby on Rails escape_javascript usage with jQuery

I have been looking at this Railscast, specifically these lines of code.

// views/reviews/create.js.erb
$("#new_review").before('
<%= escape_javascript(flash.delete(:notice)) %>
');
$("#reviews_count").html("<%= pluralize(@review.product.reviews.count, 'Review') %>");
$("#reviews").append("<%= escape_javascript(render(:partial => @review)) %>");
$("#new_review")[0].reset();

Could someone explain why escape_javascript has been used for rendering a partial, and displaying a flash notice, but not for the pluralize function?

Thanks