250+ TOP MCQs on JavaScript with YSlow and Answers

Javascript Multiple Choice Questions on “JavaScript with YSlow”.

1. How does PhantonJS use YSlow?
a) Queries
b) Statements
c) Command Line Prompt
d) Command Line Script

Answer: d
Clarification: 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.

2. What are the two output formats YSlow uses?
a) TAP, JUnit
b) JIT, TRD
c) JKP, RFD
d) TIP, KIT

Answer: a
Clarification: 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.

3. Initially, YSlow was an extension of which browser?
a) Chrome
b) Firefox
c) IE
d) Opera

Answer: b
Clarification: Initially, YSlow was an extension of Firefox. YSlow for Firefox needs Firebug to run.

4. Which of the following can be used for a deeper analysis of the web page’s performance?
a) WebPageTest
b) FireBug
c) YSlow
d) WebPageTest & FireBug

Answer: c
Clarification: 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.

5. How many rules are there in the YSlow version 2.0?
a) 23
b) 21
c) 27
d) 33

6. Which of the following is mandatory to run before running YSlow?
a) WebPageTest
b) FireBug
c) Both WebPageTest and FireBug
d) Mozilla

Answer: b
Clarification: 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.

7. How does the YSlow for Mobile work as?
a) Bookwise
b) Booklet
c) Bookmarklet
d) Bookmark

Answer: c
Clarification: The YSlow for Mobile works as bookmaklet. Bookmarklet is a JavaScript code stored as the URL of a bookmark in a web browser.

8. Which network allows you to distribute static assets like images, etc?
a) Content Delivery Network
b) Content Receiving Network
c) System Area Network
d) Local area network

Answer: a
Clarification: 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.

9. What are the three important manipulations done in a for loop on a loop variable?
a) Updation, Incrementation, Initialization
b) Initialization,Testing, Updation
c) Testing, Updation, Testing
d) Initialization,Testing, Incrementation

Answer: b
Clarification: 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.

10. 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?
a) Functional behaviour
b) Modular behaviour
c) No convenience
d) Shorthand expression

Answer: a
Clarification: 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.

Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at . He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @
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