node-get-posts-filtered.js

// All posts belonging to author with nicename "jadenbeirne"
wp.posts().filter( 'author_name', 'jadenbeirne' ).get();

// All posts in category "islands" and tags "clouds" & "sunset"
// (filter can either accept two parameters, as above where it's called with
// a key and a value, or an object of parameter keys and values, as below)
wp.posts().filter({
    category_name: 'islands',
    tag: [ 'clouds', 'sunset' ]
}).get();