Q: How does PhantonJS use YSlow?
Solution: YSlow for PhantomJS is a command line script that allows page performance analysis from live URLs, unlike YSlow for Command Line (HAR) where a pre-generated HAR file is needed in order to analyze page performance.
Q: What are the two output formats YSlow uses?
Solution: YSlow for PhantomJS is a command line script that allows page performance analysis from live URLs. YSlow for PhantomJS introduces new output formats for automated test frameworks: TAP (Test Anything Protocol) and JUnit.
Q: Initially, YSlow was an extension of which browser?
Solution: Initially, YSlow was an extension of Firefox. YSlow for Firefox needs Firebug to run.
Q: Which of the following can be used for a deeper analysis of the web page’s performance?
Solution: YSlow analyzes web page performance by examining all the components on the page, including components dynamically created by using JavaScript. It measures the page’s performance and offers suggestions for improvement.
Q: How many rules are there in the YSlow version 2.0?
Solution: 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
Q: Which of the following is mandatory to run before running YSlow?
Solution: YSlow analyzes web page performance by examining all the components on the page, including components dynamically created by using JavaScript. It is mandatory to run FireBug before running YSlow.
Q: How does the YSlow for Mobile work as?
Solution: The YSlow for Mobile works as bookmaklet. Bookmarklet is a JavaScript code stored as the URL of a bookmark in a web browser.
Q: Which network allows you to distribute static assets like images, etc?
Solution: A content delivery network (CDN) allows you to distribute your static assets like images, JavaScript files and stylesheets to geographically distributed servers. This gets the content of your page to your user’s browser faster.
Q: What are the three important manipulations done in a for loop on a loop variable?
Solution: In a for loop, the initialization, the test, and the update are the three crucial manipulations of a loop variable. Firstly the variable is created then it’s first tested then updated.
Q: What convenience does the following JavaScript code? let succ = function(x) x+1, yes = function() true, no = function() false; What convenience does the above code snippet provide?
Solution: The functions defined in this way behave exactly like functions defined with curly braces and the return keyword. The functions can be defined in a shorthand expression.
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