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JavaScript jQuery and JSON Week 1 Practice Quiz Answer

JavaScript jQuery and JSON Week 1 Practice Quiz Answer

JavaScript jQuery and JSON 

Week 1 Practice Quiz Answer 




JavaScript


Question 1)

Where does the following JavaScript code execute?


  1. <p>One Paragraph</p> 
  2. <script type=”text/javascript”> 
  3. document.write(“<p>Hello World</p>”) 
  4. </script> 
  5. <p>Second Paragraph</p>



  • In the network
  • In the browser
  • In the database server
  • In the web server



Question 2)

What happens when JavaScript runs the alert() function?


  • JavaScript pops up a dialog box and execution continues until the </alert> tag is encountered
  • JavaScript checks to see if there are any unprocessed events
  • JavaScript execution is paused and a dialog box pops up
  • A message is sent back to the PHP code to be logged on the server



Question 3)

Which of the following is not a way to include JavaScript in an HTML document?


  • By including the code between <script> and </script> tags
  • By including a file containing JavaScript using a  tag
  • By including the code the <?javascript and ?> tags
  • On a tag using an attribute like onclick=””




Question 4)

In the following code, what does the “return false” accomplish?


<a href=”js-01.htm” onclick=”alert(‘Hi’); return false;”>Click Me</a>


  • It keeps the browser from following the href attribute when “Click Me” is clicked
  • It is necessary to insure that the onclick code is at least two lines of code
  • It suppresses the pop up dialog that asks “Are you sure you want to navigate away from this page?”
  • It sets the default for the alert() dialog box



Question 5)

What happens in a normal end-user’s browser when there is a JavaScript error?


  • JavaScript logs the error to the PHP error log
  • JavaScript skips the line in error and continues executing after the next semicolon (;)
  • Nothing except perhaps a small red error icon that is barely noticeable
  • JavaScript prints a traceback indicating the line in error



Question 6)

Where can a developer find which line in a web page of JavaScript file is causing a syntax error?


  • By looking at a file on the hard disk of the system where the browser is running
  • Do a “View Source” to see the HTML source code
  • In the developer console in the browser
  • In the PHP error log



Question 7)

What does the following JavaScript do?


console.log(“This is a message”);


  • Puts the message in the browser developer console and continues JavaScript execution
  • Puts the message in the PHP console log
  • Puts the message in the browser console and pauses JavaScript execution
  • Sends the message to console.log.com



Question 8)

Which of the following is not a valid comment in JavaScript?


  • // This is a comment
  • # This is a comment
  • /* This is a comment */



Question 9)

Which of the following is not a valid JavaScript variable name?


  • $_data
  • $_DATA
  • 3peat
  • _data
  • $data



Question 10)

What is the difference between strings with single quotes and double quotes in JavaScript?


  • There is no difference
  • Double quotes strings cannot be used in JavaScript
  • Single quoted strings do not treat n as a newline
  • Double quoted strings so variable substitution for variables that start with dollar sign ($)



Question 11)

What does the following JavaScript print out?


  1. toys = [‘bat’, ‘ball’, ‘whistle’, ‘puzzle’, ‘doll’];
  2. console.log(toys[1]);


  • puzzle
  • whistle
  • doll
  • ball
  • bat



Question 12)

What value ends up in the variable x when the JavaScript below is executed?


x = 27 % 2;


  • 54
  • 13.5
  • 0
  • 27
  • 1
  • 2



Question 13)

What is the meaning of the “triple equals” operator (===) in JavaScript?


  • Both sides of the triple equals operator are converted to boolean before comparison
  • Both sides of the triple equals operator are converted to integers before comparison
  • Both sides of the triple equals operator are converted to string before comparison
  • That the values being compared are the same without any type conversion



Question 14)

How do you indicate that a variable reference within a JavaScript function is a global (i.e. not local) variable?


  • Use the keyword “global” when declaring the variable outside the function
  • Use the keyword “global” to declare the variable in the function
  • Use the keyword “var” to declare the variable in the function
  • Nothing, simply declare the variable globally before the function definition in the code