Question

How many rules are there in the YSlow version 2.0?

(a) 23

(b) 21

(c) 27

(d) 33

The question was posed to me in examination.

Asked question is from JavaScript with YSlow in chapter Performance Measures in JavaScript of JavaScript

Answer 1

Right choice is (a) 23

The explanation: There are totally 23 rules in the ruleset of YSlow (V2) namely :

Minimize HTTP Requests

Use a Content Delivery Network

Avoid empty src or href

Add an Expires or a Cache-Control Header

Gzip Components

Put StyleSheets at the Top

Put Scripts at the Bottom

Avoid CSS Expressions

Make JavaScript and CSS External

Reduce DNS Lookups

Minify JavaScript and CSS

Avoid Redirects

Remove Duplicate Scripts

Configure ETags

Make AJAX Cacheable

Use GET for AJAX Requests

Reduce the Number of DOM Elements

No 404s

Reduce Cookie Size

Use Cookie-Free Domains for Components

Avoid Filters

Do Not Scale Images in HTML

Make favicon.ico Small and Cacheable