CPT 226 Final

What is the value of selected when the following code executes?var num = undefined;var selected = num && parseFloat(num) || num || "";

""

What is returned when the following code executes?var number = 10;var highest = 18;return ( number > highest ) ? highest : number;

10

What will the value of the totalsString variable be after the following code is executed?var totals = [141.95, 212.95, 411, 10.95];totals[2] = 312.95;var totalsString = "";for (var i in totals) {totalsString += totals[i] + "|";}

141.95|212.95|312.95|10.95|

Assume userName equals "Tom" and userAge equals 22. What is displayed in a dialog box when the following statement is executed?alert(userAge + " \nis " + userName + "'s age.");

22 is Tom's age.

If you want to store a true or false value in a variable, you use the __________________ data type.

Boolean

Which native object type can you NOT create by assigning a literal value to a variable?

Date

Which of the following isn't a best practice when coding callback functions?

Throw an error if no callback function is sent.

Which of the following statements about an array of arrays is true?

Two indexes are used to access a value that's stored in an array of arrays.

The easiest way to run a web page that's already in your browser after you've made changes to the code for the page is to

click on the Reload or Refresh button

A coding error that produces the wrong results when the application is run is known as a

logic error

Which HTML element typically contains the main content of a web page?

main

In the code that follows, getElementById is a/andocument.getElementById("emailAddress");

method

Which method removes the last element from the end of an array?

pop()

A cascading method is one that

returns the object referred to by the this keyword

What property of the Radio object is used to determine if a radio button is selected?

the checked property

Which parameters are required when you call the Date constructor with number parameters?

the year and month

In a web browser, the ____________________ object is the object that's always available to JavaScript so you don't have to code its name when you call one of its methods.

window

The index value of the first element in a JavaScript array is

zero

Assuming you have a radio button with an id of "contact_via", which of the following statements selects that radio button?

$("contact_via").checked = true;

Code Example 4-3var tax = .07;var getCost = function(itemCost, numItems) {var subtotal = itemCost * numItems;var tax = 0.06;var total = subtotal + subtotal * tax;return (total);}var totalCost = getCost(25.00, 3);alert("Your cost is $" + totalCost.toFixed(2) + " including a tax of " +tax.toFixed(2)); (Refer to Code Example 4-3) What is the value of the global variable, tax?

.07

If totalMonths has a string value of "13", what does the code that follows display? var years = parseInt ( totalMonths / 12 );var months = totalMonths % 12;if ( years == 0 ) {alert ( months + " months.");} else if ( months == 0 ) {alert ( years + " years");} else {alert ( years + " years, and " + months + " months.");}

1 years, and 1 months

What is the value of scores[3] after the following code is executed?var scores = [70, 20, 35, 15];scores[3] = scores[0] + scores[2];

105

What will futureValue contain after the for loop has been executed one time?var years = 10;var annualRate = 10;var futureValue = 1000;annualRate = annualRate / 100;for ( i = 1; i <= years; i++ ) {futureValue += futureValue * annualRate;}

1100

What is the value of the totalsString variable after the following code is executed?var totals = [141.95, 212.95, 411, 10.95];totals[2] = 312.95;var totalsString = "";for (var i = 0; i < totals.length; i++) {totalsString += totals[i] + "|";}

141.95|212.95|312.95|10.95|

What is the value of selected when the following code executes?var num = "3.5";var selected = num && parseFloat(num) || num || "";

3.5

What is the value of the variable named counter after the code that follows is executed? var percent = 0.54;var isValid = true;var counter = 1;if ((percent > 0.50) && (isValid == true)) {counter += 2;if (isValid == true) {counter++;} else if (percent >= 0.50) {counter += 3;}}else {counter++;}

4

Code example 16-1var testScores = [];testScores[0] = [80, 82, 90, 87, 85];testScores[1] = [79, 80, 74, 82, 81];testScores[2] = [93, 95, 89, 100, 85];testScores[3] = [60, 72, 65, 71, 79]; (Refer to code example 16-1) This code creates a tabular structure that has

4 rows and 5 columns

After the code that follows is executed, what is the value of discountAmount?var discountAmount;var orderTotal = 200;if (orderTotal > 200) {discountAmount = orderTotal * .3;} else if (orderTotal > 100) {discountAmount = orderTotal * .2;} else {discountAmount = orderTotal * .1;}

40.0

After the code that follows is executed, the variable named userEntry will contain var userEntry = 461.95;userEntry = parseInt(userEntry);

461.95

What is the value of salesTax after the following code executes?var salesTax = 53.937;salesTax = parseFloat( salesTax.toFixed(2) );

53.94

Assume that the variables named entry and number have starting values of 9 and 3 respectively. What is the value of entry after the following statements are executed?if ((entry > 9) || (entry/number == 3)) {entry--;} else if (entry == 9) {entry++;} else {entry = 3;}

8

Which of the following is NOT a relational operator?

=

Which of the following operators does NOT perform type coercion?

===

Which of the following statements about for and for-in loops is true?

A for loop processes undefined elements, but a for-in loop skips over them.

How could the following code be improved?var calculateSalesTax = function(amount, taxRate, getTaxableAmount) {var taxable = amount;taxable = getTaxableAmount(amount);var tax = taxable * taxRate;return (isNaN(tax))? "Invalid calculation." : tax;};

Add code to check that getTaxableAmount is a function before calling it.

How could the following code be improved?var calculateSalesTax = function(amount, taxRate, getTaxableAmount) {var taxable = amount;taxable = getTaxableAmount(amount);var tax = taxable * taxRate;return (isNaN(tax))? "Invalid calculation." : tax;}; Question options:

Add code to check that getTaxableAmount is a function before calling it.

Code example 14-2window.onload = function() {var topSites = ["Google", "Facebook", "Twitter"];var links = $("top_sites").getElementsByTagName("a");for (var i in topSites) {links[i].text = topSites[i];links[i].onclick = (function(name) {return function() {alert("You clicked on " + name);};})(topSites[i]);}}; (Refer to code example 14-2) If the onclick event handlers for the links were attached directly instead of within an IIFE, what would happen?

All the links would display the name of the last site in the array.

What will happen first as soon as the page that contains the following code loads?window.onload = function() {alert("Welcome to the Calculate Cost page!");$("ship").onclick = shipCost();};

An alert dialog box will display with the message "Welcome to the Calculate Cost page!".

Which of the following statements about associative arrays is true?

An associative array uses strings as the indexes.

What is the value of random after the following code executes?var random = Math.floor(Math.random() * 10);random = random + 1;

An integer between 1 and 10

Given the following lines of code, what will be displayed in successive dialog boxes?var answers = [ "C", "B", "D", "A" ];delete answers[3];for ( var i in answers ) {alert(answers[i]);}

C, B, D

Given the following lines of code, what will be displayed in successive dialog boxes?var answers = [ "C", "B", "D", "A" ];delete answers[3];for ( var i = 0; i < answers.length; i++ ) {alert(answers[i]);}

C, B, D, undefined

What happens when you create an array of one or more elements but don't assign values to those elements?

Each element is set to undefined.

If a case label of a switch statement doesn't contain a break statement, what will the code execution do?

Fall through to the next label

What is displayed when the following code executes?var statusCode = "403";switch ( statusCode ) {case "200": alert("OK"); break;case "403": alert("Forbidden"); break;case "404": alert("Not Found"); break;default: alert("Unknown Status"); break;}

Forbidden

Which of the following statements about function declarations and function expressions is NOT true?

Function declarations cannot return a value.

If a numerical operation returns a number greater than the largest possible JavaScript value, it returns

Infinity

Code example 14-2window.onload = function() {var topSites = ["Google", "Facebook", "Twitter"];var links = $("top_sites").getElementsByTagName("a");for (var i in topSites) {links[i].text = topSites[i];links[i].onclick = (function(name) {return function() {alert("You clicked on " + name);};})(topSites[i]);}}; (Refer to code example 14-2) When the IIFE is invoked, what happens to the array element (topSites[i]) that's passed as an argument

It becomes the name parameter.

What does the optional limit parameter of the split() method do?

It specifies the maximum number of elements in the new array.

What is the value of the message variable after the following code executes?var message = "";for (var i = 0; i < 5; i++ ) {message += "L:" + i + ",";}

L:0,L:1,L:2,L:3,L:4,

What is displayed by the alert dialog box after the following code executes?var name = "Donny,Duck";var index = name.indexOf(","); var lastName = name.substr(index + 1, name.length - 1);;alert("Last name: " + lastName);

Last name: Duck

If the current date is Monday, February 26, 2017, what will be displayed by the alert dialog box after the following code executes?var thisDay = new Date(); alert(thisDay.toDateString());

Mon Feb 26 2017

What does the code that follows do?var image = new Image();image.src = "logo.jpg";

Preloads "logo.jpg".

What is displayed when the following code executes?var rate = 0.1;if ( isNaN(rate) ) {alert("Rate is not a number.");} else if (rate < 0) {alert("Rate cannot be less than zero.");} else if (rate > 0.2) {alert("Rate cannot be greater than 20%.");} else {alert("Rate is valid.");}

Rate is valid.

What does the second statement that follows do?var numbers = [1, 2, 3, 4];numbers.length = 0;

Removes all the elements in the array.

Which of the following is NOT true about the script mode feature of ECMAScript 5?

Script mode is supported by all older browsers.

What does the code that follows do?$("email").firstChild.nodeValue = "Entry is invalid.";

Sets the text for the element with "email" as its id attribute.

In the following code, what does the bind method do?var tax = {rate: 0.075,calc: function(sub) { return sub + (sub * this.rate)).toFixed(2); },displayFullPrice: function(subtotal) {return function() {alert(this.calc(subtotal));}.bind(this);} };

Sets the value of the this keyword in the displayFullPrice method to the tax object.

Code example 14-1var createClickCounter = function() {var count = 0;var clickCounter = function() {count++;console.log(this.id + " + count is " + count);};return clickCounter;};window.onload = function() {$("btnCount").onclick = createClickCounter();}; (Refer to code example 14-1) Why is there a pair of parentheses after createClickCounter in the statement in the onload event?

So the outer function runs and returns the definition of the inner function.

Code example 14-1var createClickCounter = function() {var count = 0;var clickCounter = function() {count++;console.log(this.id + " + count is " + count);};return clickCounter;};window.onload = function() {$("btnCount").onclick = createClickCounter();}; (Refer to code example 14-1) Which of the following statements about this code is not true?

The count variable stays alive after the outer function runs and can be accessed by outside code.

What is displayed in the alert dialog box after the following code is executed?var items = 3;for (var i = 1; i <= items; i++) {var result = 1;for (var j = i; j >= 1; j--) {result *= j;}alert("The factorial of " + i + " = " + result);}

The factorial of 3 = 6

Which of the following statements about the sort() method of an array is NOT true?

The function passed to the sort() method returns a value of true or false.

What is displayed in the alert dialog box after the following code is executed?var scores = [70, 20, 35, 15];scores[scores.length] = 40;alert("The scores array: " + scores);

The scores array: 70,20,35,15,40

What happens when a string doesn't include the separator that's specified in the parameter of the split() method?

The split() method returns an array that contains the string as its only element.

Code Example 4-1var name = prompt("Enter the name to print on your tee-shirt");while (name.length > 12) {name = prompt("Too long. Enter a name with fewer than 12 characters.");}alert("The name to be printed is " + name.toUpperCase()); (Refer to Code Example 4-1) What will happen if the user enters Willy Shakespeare at the first prompt?

The user will be prompted to enter a different name

Code example 13-1var evt = {attach: function(node, eventName, func) {if (node.addEventListener) {node.addEventListener(eventName, func);} else if (node.attachEvent) {node.attachEvent("on" + eventName, func);}},detach: function(node, eventName, func) {if (node.removeEventListener) {node.removeEventListener(eventName, func);} else if (node.detachEvent) {node.detachEvent("on" + eventName, func);}},preventDefault: function(e) {e = e || window.event;if ( e.preventDefault ) { e.preventDefault(); }else { e.returnValue = false; }}}; (Refer to code example 13-1.) This is the code for a cross-browser compatible library for working with events. It contains

Three methods

What is displayed when the following code executes?var age = 19, score = 750;if ( age >= 21 && score >= 700 ) {alert ("Loan approved");} else if ( age >= 21 && score >= 650 ) {alert ("Cosigner needed.");} else if ( age >= 18 && score >= 680 ) {alert ("Two cosigners needed.");} else {alert ("Loan denied.");}

Two cosigners needed.

Which of the following is NOT one of the three testing phases of a JavaScript application?

Using the developer tools to check the DOM

After the code that follows executes, the alert dialog box will display var userCost = 29.94999;alert("Your cost is $ " + parseFloat(userCost.toFixed(2)));

Your cost is $ 29.95

To make sure that the HTML and CSS for a web page are interpreted the same way by all browsers, you can use

a Javascript shiv and the normalize.css style sheet

The following code is an example ofvar getInvoice = function( subtotal, taxRate ) {var invoicePrototype = {getTotal: function() {return this.subtotal + (this.subtotal * this.taxRate);}};var invoice = Object.create( invoicePrototype );invoice.subtotal = subtotal;invoice.taxRate = taxRate;return invoice;}

a factory function

Within a CSS style rule, a property declaration inculdes

a property and a value

The following code will move the focus to window.onload = function() {$("join_up").onclick = signUp;$("user_first_name").focus();};

a textbox with id = "user_first_name"

Sometimes, validating the HTML code for a web page will help you debug an application, because

a trivial HTML error can cause other types of errors

When you use the relational operators, you can compare

a variable with a literal value a variable with another variable a variable with an arithmetic expression

to make a website available to other computers over a network, the website is stored on

a web server

Code Example 4-2var add = function( x, y ) {return ( x + y );}alert( add (5, 3) ); (Refer to Code Example 4-2) The function in this example

accepts 2 parameters and returns 1 value

Given the following code, which of the following statements displays "John Smith is 29"?var employee = [];employee["name"] = "John Smith";employee["age"] = 29;

alert(employee["name"] + " is " + employee["age"]);

What elements would the style rule that follows apply to? .red { color: red; }

all elements with the class named red

When a client requests a dynamic web page, the HTML is generated by

an application server

The code that follows has a bug in it because the second use of the variable named salesTax is spelled with all lowercase letters (salestax). var calculateTax = function(subtotal,taxRate) {var salesTax = subtotal * taxRate;salestax = parseFloat(salesTax.toFixed(2));return salesTax;}Assuming that there are no other problems and that you're using strict mode, what will happen when this code is executed?

an error will occur because salestax hasn't been declared

In a simple assignment statement, you use the _____________________ operator.

assignment

For the following code, an event handler named investment_change isvar investment_change = function() {var years = parseInt( $("years").value );alert("Years: " + years);}window.onload = function() {$("investment").onchange = investment_change;}

attached to the onchange event of a control with an id of "investment".

The condition for a while loop is tested

before the statements in the loop are executed

Which HTML event occurs when an element on the page loses focus?

blur

The class attribute

can be used by CSS to apply the same formatting to more than one HTML element

Which of the following statements is false? A JavaScript identifier

can start with a number

The following codevar display_error = function(message) {alert("Error: " + message);}

creates a function and stores it in a variable named display_error

To view the changes that have been made to the DOM for a page by the JavaScript, you can

display the HTML for the page in Chrome's Elements panel

Code Example 4-2var add = function( x, y ) {return ( x + y );}alert( add (5, 3) ); (Refer to Code Example 4-2) The alert method in this example

displays a dialog box with a value of 8

Given a Date object named due_date, which of the following statements sets the month to February?

due_date.setMonth(1);

Code example 13-1var evt = {attach: function(node, eventName, func) {if (node.addEventListener) {node.addEventListener(eventName, func);} else if (node.attachEvent) {node.attachEvent("on" + eventName, func);}},detach: function(node, eventName, func) {if (node.removeEventListener) {node.removeEventListener(eventName, func);} else if (node.detachEvent) {node.detachEvent("on" + eventName, func);}},preventDefault: function(e) {e = e || window.event;if ( e.preventDefault ) { e.preventDefault(); }else { e.returnValue = false; }}}; (Refer to code example 13-1.) This is the code for a cross-browser compatible library for working with events. To attach an event handler named toggleH2 to the click event of a heading with "q1" as its id, you code which of the following statements:

e.attach($("q1"),onclick,toggleH2;

Now that HTML5 is used by all modern browsers, the HTML div element should be used primarily for grouping

elements for JavaScript and jQuery applications

Given an event object that's stored in a variable named evt, which of the following statements will cancel the default action in modern browsers?

evt.preventDefault();

When the statement that follows is executed, JavaScript var rate = parseFloat(document.getElementById("rate").value);

executes the getElementById() method, gets the value property of the resulting object, and executes the parseFloat() method on that value

Which method accepts a function that is executed once for each element and returns a new array that contains the elements that meet the condition specified in the function?

filter()

Which of these for statements displays even numbers from 0 to 10?

for ( var i = 0; i <= 10; i += 2 ) { alert( i ); }

The type of loop that provides for varying the value of an index (or counter) is a

for loop

Which of the following is a valid function declaration for a function named getUserAge() that accepts one parameter?

function getUserAge(user)

Code Example 4-3var tax = .07;var getCost = function(itemCost, numItems) {var subtotal = itemCost * numItems;var tax = 0.06;var total = subtotal + subtotal * tax;return (total);}var totalCost = getCost(25.00, 3);alert("Your cost is $" + totalCost.toFixed(2) + " including a tax of " +tax.toFixed(2)); (Refer to Code Example 4-3) Which variable represents the function expression?

getCost

Each function has a this keyword whose value depends on

how the function was invoked

When you "comment out" JavaScript code, the code is __________________________ when the page is tested.

ignored

Code example 14-1var createClickCounter = function() {var count = 0;var clickCounter = function() {count++;console.log(this.id + " + count is " + count);};return clickCounter;};window.onload = function() {$("btnCount").onclick = createClickCounter();}; (Refer to code example 14-1) The count variable of the outer function is

in private state.

If possible, the parseInt method converts the string that's passed to it to a/an _____________________________.

integer

Which of the following will test whether a Boolean variable named isValid is true?

isValid == true isValid !isValid == false

A binary search is better for large arrays than a sequential search because

it discards half the array on each comparison.

Because window is the global object of JavaScript,

it is not necessary to code the object name before the method name

A cascading method can be chained with other methods. This style of coding is sometimes called fluent because

it reads like a sentence and is easy to understand

An IIFE should always be coded within parentheses because

it's a coding convention that lets other programmers know it's an IIFE.

Which method returns the elements of an array in a string separated by a comma?

join()

Which keyboard event occurs when a key has been released?

keyup

Which mouse event occurs when the mouse pointer hovers over an HTML element?

mouseover

When you test an application with Chrome's developer tools and a breakpoint is reached, you can view the current data by

moving the mouse pointer over the name of a variable in the Sources panel

When writing a recursive function, what kind of function expression should you use to make sure the function will always be able to call itself.

named

The equal to (==) and not equal to (!=) operators should

not be used to compare floating-point numbers

In the code that follows, document is a/andocument.getElementById("emailAddress");

object

In the code that follows, window is a/an ____________________________.window.prompt("Enter your name");

object

If an arithmetic expression isn't evaluated the way you want it to be due to the order of precedence, you can override that order by using ____________________.

parentheses

What can you use to clarify the order of relational and logical operations in a conditional expression?

parentheses

What sequence of components does an HTTP URL consist of before the filename?

protocol, domain name, path

Which method accepts a function that combines all the elements in the array and then returns the resulting value?

reduce()

A for-in loop doesn't

require expressions to intialize, test, and increment an index counter

To provide JavaScript in the body of an HTML document, you code an HTML __________________ element that contains the JavaScript.

script

How can you clear a check from a Checkbox object?

set its checked property to false

Which of the following statements runs the newTimer function every 3 seconds?

setInterval(newTimer, 3000);

Which of the following statements runs the newTimer function once after 3 seconds?

setTimeout(newTimer, 3000);

Which of the following methods of the Array object accepts a callback function as an argument?

sort

Code example 16-1var testScores = [];testScores[0] = [80, 82, 90, 87, 85];testScores[1] = [79, 80, 74, 82, 81];testScores[2] = [93, 95, 89, 100, 85];testScores[3] = [60, 72, 65, 71, 79]; (Refer to code example 16-1) Which of the following returns a value of 89?

testScores[2][2]

Which of the following statements performs a case-insensitive comparison of the strings named text1 and text2?

text1.toLowerCase() == text2.toLowerCase()

A cross-browser compatible method for attaching an event handler must provide parameters for

the HTML node, the event, and the event handler

What method of the Math object can be used to return the largest value from the values that are passed to it?

the Math.max method

When you test an application with Chrome's developer tools and a breakpoint is reached, you can click

the Step Into button to execute the current statement and move to the next statement

Code example 13-1var evt = {attach: function(node, eventName, func) {if (node.addEventListener) {node.addEventListener(eventName, func);} else if (node.attachEvent) {node.attachEvent("on" + eventName, func);}},detach: function(node, eventName, func) {if (node.removeEventListener) {node.removeEventListener(eventName, func);} else if (node.detachEvent) {node.detachEvent("on" + eventName, func);}},preventDefault: function(e) {e = e || window.event;if ( e.preventDefault ) { e.preventDefault(); }else { e.returnValue = false; }}}; (Refer to code example 13-1.) This is the code for a cross-browser compatible library for working with events. In the code for the attach method, the if clause provides for modern browsers and the else if clause provides for older IE browsers. This shows that older browsers require the use of

the attachEvent method of a node object and the prefix "on" for the event name

To remove the focus from a control, what method do you use?

the blur method

What event occurs when the user selects a new item from a select list?

the change event

The delete operator deletes

the contents of an element in an array

Code example 13-1var evt = {attach: function(node, eventName, func) {if (node.addEventListener) {node.addEventListener(eventName, func);} else if (node.attachEvent) {node.attachEvent("on" + eventName, func);}},detach: function(node, eventName, func) {if (node.removeEventListener) {node.removeEventListener(eventName, func);} else if (node.detachEvent) {node.detachEvent("on" + eventName, func);}},preventDefault: function(e) {e = e || window.event;if ( e.preventDefault ) { e.preventDefault(); }else { e.returnValue = false; }}}; (Refer to code example 13-1.) This is the code for a cross-browser compatible library for working with events. In the code for the preventDefault method, the first statement sets e equal to either

the event object that's passed to the event handler or the window.event object

What method of the Date object gets the day of the month in local time?

the getDate method

What method of the String object searches the string for an occurence of the specified search string?

the indexOf method

When you call a constructor, you create an instance of the object type that inherits

the methods of that type

To display data in a span element, you can use the firstChild property to get a pointer to the Text node. Then, what property of the Text node can you use to set the value that's displayed in the span element?

the nodeValue property

What does the length property of an array return?

the number of elements in the array

When you develop a web page, you should use HTML to provide

the structure and content for the page

What method of the Number object returns a string with the number rounded to the specified number of decimal places?

the toFixed method

For a Textarea object, what property do you use to get the text that has been entered into the text area?

the value property

When a client requests a static web page, the HTML is generated by

the web browser

What value is returned by the following expression? !isNaN("12.345")

true

To load a web page into a web browser, you can

type the URL of the web page into the browser's address bar

Which method adds one or more elements to the beginning of an array?

unshift()

Which of the following statements is NOT a valid way to create a date object named birthday?

var birthday = "12/2/1978";

Which of the following will create an event handler that is attached to the mouseout event for a textbox with id = "username" so that the user's entry, formatted in all lowercase, will be displayed in an alert? Assume the following $ function has already been coded in the page:var $ = function(id) {return document.getElementById(id);};

var getUserName = function() {var name = $("username").value;alert("Your username is " + name.toLowerCase());};window.onload = function() {$("username").onmouseout = getUserName;};