JavaScript, jQuery, and JSON Coursera Quiz Answers

JavaScript, jQuery, and JSON Week 01 Quiz Answers

Q1. Where does the following JavaScript code execute?

<p>One Paragraph</p> 
<script type="text/javascript"> 
document.write("<p>Hello World</p>") 
</script> 
<p>Second Paragraph</p>

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

Q2. What happens when JavaScript runs the alert() function?

• 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
• JavaScript pops up a dialog box and execution continues until the </alert> tag is encountered

Q3. Which of the following is not a way to include JavaScript in an HTML document?

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

Q4. In the following code, what does the “return false” accomplish?

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

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

Q5. 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 (;)
• JavaScript prints a traceback indicating the line in error
• Nothing except perhaps a small red error icon that is barely noticeable

Q6. Where can a developer find which line in a web page of JavaScript file is causing a syntax error?

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

Q7. What does the following JavaScript do?

console.log("This is a message");

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

Q8. Which of the following is not a valid comment in JavaScript

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

Q9. Which of the following is not a valid JavaScript variable name?

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

Q10. What is the difference between strings with single quotes and double quotes in JavaScript?

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

Q11. What does the following JavaScript print out?

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

• doll
• whistle
• puzzle
• bat
• ball

Q12. What value ends up in the variable x when the JavaScript below is executed?

x = 27 % 2;

• 2
• 0
• 54
• 13.5
• 27
• 1

Q13. What is the meaning of the “triple equals” operator (===) in JavaScript?

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

Q14. How do you indicate that a variable reference within a JavaScript function is a global (i.e. not local) variable?

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

JavaScript, jQuery, and JSON Week 02 Quiz Answers

Q1. Which of the following is a template that defines the shape of an object that is created?

• Method
• Message
• Inheritance
• Instance
• Class

Q2. Which of the following describes a feature which we would expect from a programming language that supported first class functions?

• The ability to have a variable number of parameters when calling a function
• The ability to define a function and assign the function to a variable
• The ability for a function not to return a value (i.e. void functions)
• The ability to omit parameters and have the omitted parameters default to a value
• The ability to return a value from a function

Q3. What is the keyword / predefined variable that is used in a JavaScript class definition to refer to the “current instance” of the class?

• $this
• _self
• self
• me
• this

Q4. What do these two statements in JavaScript accomplish?

data.stuff = "hello"; 
data['stuff'] = "hello";

• The second statement is a syntax error in JavaScript
• These two statements accomplish the same thing
• The first statement creates an object and the second creates a dictionary
• The first statement is a syntax error in JavaScript

Q5. How is the constructor defined in JavaScript class compared to how the constructor is defined in a PHP class?

• The PHP constructor method is called __construct() and the JavaScript constructor method is called construct()
• A PHP constructor is a method named __construct() and a JavaScript constructor is code in the outer function definition
• The PHP and JavaScript constructor patterns are the same
• JavaScript does not support the notion of running a “constructor” when objects are created.

JavaScript, jQuery, and JSON Week 03 Quiz Answers

Q1. What is the purpose of the following JQuery ready() call?

$(document).ready(function(){
 window.console && console.log('Hello JQuery..');
});

• Register a function that will be called when the HTML document is completely loaded
• Clear the browser window so drawing can start in the upper left hand corner
• Ascertain if the document is ready to load
• Enable the retrieval of data in the JSON format

Q2. What portion of the DOM (Document Object Model) will be affected by the following JQuery statement:1$('#para').css('background-color', 'red');

• All elements in the DOM
• A tag with a class attribute of “para”
• All tags with a class attribute of “para”
• A tag with an id attribute of “para”

Q3. What does the following JQuery code do

1$('#spinner').toggle();

• Call the global JavaScript function toggle with the spinner tag as its parameter
• Hide or show the contents of a tag with the id attribute of “spinner”
• Indicate that page loading has completed
• Switch the spinner.gif with the image spinner_toggle.gif

Q4. What will the following JQuery code select from the given HTML?

<p id="p">two
  <input type="text" name="one" value="three" title="four">
  <input type="text" name="five" class="p" value="p">
</p>
<script>
$('#p').find('input[name="one"]').val();
</script>
 

• one
• three
• four
• two
• five

Q5. Which of the following is not a primitive type supported in JSON?

• url
• boolean
• string
• integer
• array

Q6. In the following JSON, how would you print the value “six”?

data = {'one':'two', 'three': 4,
  'five' : [ 'six', 'seven' ],
  'eight' : { 'nine' : 10, 'ten' : 11  }
}

• alert(data.five[0])
• alert(data.eight.nine)
• alert(five)
• alert(data[‘six’])
• alert(five.six)

Q7. What would the following JavaScript print out?

data = {'one':'two', 'three': 4,
  'five' : [ 'six', 'seven' ],
  'eight' : { 'nine' : 10, 'ten' : 11  }
};
alert(data.eight.nine);

• six
• nine
• 10
• seven
• 11

Q8. In the following code, what would you expect in the variable named “data”?

$.getJSON('json.php', function(data) {
    $("#back").html(data.first);
    window.console && console.log(data);
 });

• A string that is the entire HTTP response of the output from the script json.php
• All of the tags from the DOM with a class attribute of “back”
• The tag in the DOM that has an id attribute of “first”
• Either a JavaScript object or list depending on the returned output of the script json.php

Q9. Which of the following JQuery statements will hide spinner.gif in this HTML?

<div id="chatcontent">
 <img src="spinner.gif" alt="Loading..."/>
</div>

• $(“spinner.gif”).suppress();
• $(“spinner.gif”).alt \= \-1;
• $(“img>spinner.gif”).hide();
• $(“#chatcontent”).hide();
• $(“.chatcontent”).off();

Q10. What does the PHP function json_encode() do ?

• Encodes the less\-than and greater\-than characters to make a string safe for JSON
• Takes a PHP object or list and serializes it into a JSON string representation
• Reads a JSON string representation and converts it to a PHP object or list
• Encodes all non\-printing characters with their hexadeciamal equivalents

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