Method 1:

User-agent: *
Disallow: /wp-admin/
Disallow: /wp-includes/
allow: /wp-content/plugins/
allow: /wp-content/themes/

Method 2:

#Googlebot
User-agent: Googlebot
Allow: *.css
Allow: *.js

# Other bot spider
User-agent: *
Disallow: /wp-admin/
Disallow: /wp-includes/