INF-306 HTML5 Application Development Questions and Answers

A CSS flexible box layout is created by applying the display property to a container with either flex or inline-flex. This establishes the element as a flex container and causes its child elements to become flex items. The flex-direction property defines the direction of the main axis and accepts row, row-reverse, column, and column-reverse, allowing items to flow horizontally, vertically, or in reverse order. The align-items property controls how flex items are aligned along the cross axis, with values such as flex-start, flex-end, and center. The direction property controls writing direction and accepts ltr for left-to-right text flow or rtl for right-to-left text flow. Finally, order is applied to individual flex items and accepts an integer value, represented here as “any,” because any numeric order value can be used to rearrange item display order without changing the document source order. References/topics: CSS flexbox, flex containers, flex items, main axis, cross-axis alignment, writing direction, item ordering.

The correct answer is A because the code at line 03 creates an object by calling a constructor function with the new keyword. A constructor function must be declared with the same identifier used in the new Student( " David " , " Hamilton " ) expression. Inside the constructor, instance members should be assigned through this, because this refers to the newly created object. Option A correctly initializes this.firstname, this.lastname, and this.fullname, so beststudent.fullname is available at line 04 and evaluates to " David Hamilton " . Option B is invalid JavaScript syntax because var student(firstName, lastName) is not a valid function declaration. Option C is also invalid syntax for the same reason: var Student(firstname, lastname) cannot declare a constructor. Option D uses a valid function declaration, but it assigns firstname, lastname, and fullname without this, which creates or references non-encapsulated variables rather than properties of the constructed object. References/topics: JavaScript constructor functions, new keyword, object instance properties, this, custom classes.

First drop-down: var xhr = new XMLHttpRequest();

Second drop-down: if(xhr.status===200){

Third drop-down: responseObject = JSON.parse(xhr.responseText);

The script must first create an XMLHttpRequest object, so the correct first selection is var xhr = new XMLHttpRequest();. This object performs the asynchronous request for menu.json. After the request finishes, the onload callback executes. The response should be processed only when the request succeeds, so the correct status check is if(xhr.status===200){; HTTP status 200 means the file was successfully retrieved. Status codes 403, 404, and 500 represent forbidden access, missing resource, and server error conditions, so they are not appropriate for normal JSON processing. The JSON file is returned as plain text through xhr.responseText, so it must be converted into a JavaScript object with JSON.parse(xhr.responseText). Once parsed, the code can access responseObject.menu[i].Entree, Price, and Description inside the loop and build the display output. responseXML is incorrect because the source file is JSON, not XML.

The correct features are saving temporary authentication tokens and passing form data to a confirmation page. sessionStorage provides a storage area scoped to the current origin and browser tab, and its data is retained only for the duration of the page session. That makes it appropriate for short-lived application state that must survive page reloads or navigation within the same workflow, but should not remain permanently available after the session ends. Passing form data from an entry page to a confirmation page is a classic session-scoped use case because the data is needed briefly during a multi-page transaction. Temporary authentication tokens can also fit the session-storage model when the token should be tied to the active browser session rather than persisted across future visits. Customized UI/UX settings usually need to persist across sessions, so localStorage or server-side user preferences are more appropriate. Game progress saved for future use is also persistent state, not session-only state. Passing data to a function is ordinary JavaScript memory usage and does not require Web Storage. References/topics: application state management, Web Storage API, sessionStorage, temporary workflow data, session-scoped tokens.

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The valid entry is A, assuming the OCR-corrupted option represents the intended secret-code format: four letters, a hyphen, two digits, a hyphen, four digits, a hyphen, and four letters. The HTML pattern attribute defines a regular expression that an input value must satisfy during constraint validation. MDN specifies that pattern is used to define a regular expression the input value must match. In the intended pattern, the first group must contain exactly four alphabetic characters, the second group exactly two numeric digits, the third group exactly four numeric digits, and the final group exactly four alphabetic characters. Option A satisfies that structure: kukX is four letters, 04 is two digits, 4938 is four digits, and WJDF is four letters. Option B fails because the final group Uhj6 contains a digit. Option C fails because the first group includes a digit and the digit grouping/hyphen structure is wrong. Option D fails because 23h contains a letter where only digits are allowed. References/topics: HTML5 form validation, pattern attribute, regular-expression validation, text input constraints.

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The correct answer is A. Applying float: right to an image removes the image from the normal inline flow and moves it to the right side of its containing block. Inline content, such as text, is then allowed to flow around the floated image. Because the image is anchored on the right, available text space is primarily on the left side of the image, and the text can continue above, beside, and below the floated region according to the surrounding layout. This is the classic use case for floating images within article-style content, where text wraps around a visual element rather than forcing the image to occupy an entire line. Option B is incomplete because it omits the important left-side wrapping behavior. Option C describes the opposite direction: an image floated left with text appearing to its right. Option D also describes float: left, not float: right. References/topics: CSS float, floated images, text wrapping, normal flow, content positioning.

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Option C is the only segment that correctly combines three required pieces: two contributing < input > controls, a named < output > control, and executable form-level logic that assigns a calculated value into that output. The HTML < output > element is specifically designed as a container for the result of a calculation or user action, and its for attribute identifies the controls that contributed to the calculation by using a space-separated list of element identifiers or associated names in the form workflow. MDN’s reference demonstrates this exact pattern: two input values are added, and the result is assigned to an < output > element whenever input changes. Option A renders literal text inside < output > but does not update it. Option B has no < output > element at all, so it cannot satisfy the requirement. Option D declares an output but lacks an oninput handler or script assignment, so the displayed value never changes. References/topics: HTML5 forms, < output > element, for attribute, form input events, calculated form results.

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The two likely causes are undersized touch targets and overlapping input regions. Touch input is less spatially precise than mouse input because the contact area of a finger is larger and less exact than a pointer cursor. Microsoft’s touch-target guidance states that interactive UI elements must be large enough for users to access accurately, and recommends a target size around 7.5 mm square, approximately 40 × 40 pixels on a 135 PPI display. Earlier Microsoft touch-design guidance similarly emphasizes that controls must be appropriately sized for touch and identifies approximately 9 mm as a minimum targeting area. Therefore, small input buttons may fail to trigger because the user is not actually hitting the active target area. Overlap is also a valid cause: when two active regions occupy the same physical screen area, hit testing may route the touch to a different element, or the effective target area may be reduced. W3C accessibility guidance explicitly treats overlapping targets as reducing measurable target size unless the overlapping controls perform the same action. Event handlers themselves are not the defect; they are the normal mechanism for processing input. “Touch screen not initialized” is not a standard HTML5 application cause. References/topics: touch input, event handling, hit testing, target size, overlapping controls.

display: grid;

grid-template-columns: repeat(6, 1fr);

grid-template-rows: 50px 50px 150px 150px 100px;

grid-gap: 10px 15px;

The correct grid definition starts with display: grid;, which turns the element into a CSS Grid container. To explicitly create six equal-width columns, the correct property is grid-template-columns, and the most efficient value is repeat(6, 1fr). The repeat() function avoids writing 1fr six separate times, while 1fr assigns each column one equal fraction of the available grid width. The five row sizes must be explicitly declared with grid-template-rows, using the exact varied values shown: 50px 50px 150px 150px 100px. This creates five rows with fixed pixel heights. For the spacing requirement, grid-gap: 10px 15px; is the correct shorthand. The first value controls the row gap, so rows are separated by 10px; the second value controls the column gap, so columns are separated by 15px. References/topics: CSS Grid containers, explicit grid tracks, grid-template-columns, grid-template-rows, repeat(), fractional units, grid gaps.

The statement draws a semicircle at the specified point. The arc() method of the Canvas 2D API adds a circular arc to the current path. Its core parameters are the center point x, y, the radius, the starting angle, the ending angle, and an optional direction flag. In this expression, x and y define the center of the arc, and r defines its radius. The start angle is 0 radians, and the end angle is Math.PI radians. Since Math.PI represents 180 degrees, the path covers exactly half of a full circle. The final argument, true, tells the canvas context to draw the arc counterclockwise rather than using the default clockwise direction; however, the angular span remains half of the circumference. The call does not draw a complete visible shape unless the path is later stroked or filled, but the geometric path being created is a semicircular arc. It is not a straight line, square, or full circle. References/topics: Canvas 2D context, arc() method, radians, path construction, drawing arcs and circles.

The value stored in num is the number of key-value pairs currently stored in localStorage. The localStorage object implements the Web Storage Storage interface, which stores data as named string key/value entries for the current origin. Its length property is read-only and returns the number of data items stored in that Storage object, not the size of the stored data and not the remaining capacity. MDN’s Storage reference explicitly defines length as returning the number of data items stored, and its example shows that after three items are added to localStorage, localStorage.length returns 3. Therefore, if the storage area contains five named entries, num receives 5; if it contains no entries, num receives 0. Option A is incorrect because available bytes are not exposed through length. Option B is unrelated to Web Storage. Option C is incorrect because browser storage quota or capacity is separate from the length property. References/topics: Web Storage API, localStorage, Storage.length, key-value storage, application state.

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First drop-down: navigator.geolocation

Second drop-down: navigator.geolocation

Third drop-down: getCurrentPosition(showLocation)

The correct API object is navigator.geolocation because browser-based geographic location is exposed through the Geolocation API, not through window.location. window.location represents the current page URL and navigation state; it does not provide latitude or longitude. The first selection checks whether the browser supports geolocation by evaluating navigator.geolocation. Inside the block, the same object must be used to request the user’s current position. The correct method is getCurrentPosition(showLocation), which requests the device’s current location and passes a position object to the callback function when the location is available. The callback then reads position.coords.latitude and position.coords.longitude and displays those values with alert(). The alternatives that pass window.location are incorrect because they provide page-location information rather than geographic coordinates. The alternatives that call showLocation(...) directly are also incorrect because the browser must first retrieve the actual position object. References/topics: Geolocation API, navigator.geolocation, getCurrentPosition(), callback functions, latitude and longitude.

First blank: class Dog extends Pet {

Second blank: super(name, breed);

The correct syntax for deriving one JavaScript class from another is extends, so the derived class declaration must be class Dog extends Pet {. This creates Dog as a subclass of Pet, allowing Dog instances to inherit members defined by the Pet constructor, including name, breed, and the show() function assigned inside the parent constructor. Inside a derived class constructor, super() must be called before using this. The call super(name, breed); invokes the parent Pet constructor and passes the values required to initialize the inherited name and breed properties. Pet(name, breed); is incorrect because a class constructor cannot be invoked like a normal function. Pet.constructor(name, breed); is also incorrect because it does not call the parent constructor for the current instance. After super() runs, the Dog constructor can safely assign subclass-specific properties such as price and gender. References/topics: JavaScript classes, inheritance, extends, derived constructors, super(), custom class creation.

pattern → Provides a way to set a regular expression that the value must match

placeholder → Provides a way to set default text that displays until focus is placed in an element

required → Provides a way to set form elements as mandatory

multiple → Provides a way to allow more than one file or email address in a single input

The correct matches are based on standard HTML5 form validation and input-attribute behavior. The pattern attribute defines a regular expression that the input value must satisfy before the form can be submitted successfully. It is commonly used for structured values such as phone numbers, codes, postal formats, or custom identifiers. The placeholder attribute supplies short hint text inside an input field, helping the user understand the expected value before entering data. The required attribute makes a form control mandatory; if the field is empty, constraint validation prevents successful submission. The multiple attribute allows a single input to accept more than one value, specifically for controls such as input type= " file " and input type= " email " , where users may upload multiple files or enter multiple email addresses. The maxlength attribute is not used in these matches because it limits the maximum number of characters that can be entered, but none of the listed descriptions asks for character-length restriction. References/topics: HTML5 form attributes, constraint validation, pattern, placeholder, required, multiple, input validation.

The correct causes are insufficient input target size and overlapping input areas. Touch interaction depends on hit testing: the browser or platform determines which element occupies the touched screen coordinate and dispatches the event to that element. If a button’s active area is too small, the user’s finger may visually appear to tap the button while the actual touch coordinate falls outside the actionable target. Microsoft’s touch-target guidance recommends touch targets around 7.5 mm square, approximately 40 × 40 pixels on a 135 PPI display, to support reliable activation. Overlap is also a valid cause because one element can partially cover or compete with another during hit testing; W3C target-size guidance notes that overlapping areas should not be counted as usable target area unless the overlapping controls perform the same action. Event handlers are not the problem by themselves; they are the standard mechanism for detecting user input. “Touch screen not initialized” is not a normal HTML5 application-level cause. References/topics: touch input, event handling, hit testing, target size, overlapping controls.

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The correct segment is D because named grid-region layouts are defined with grid-template-areas. This CSS Grid property specifies named grid areas, establishes the cells in the grid, and assigns names to those cells. The syntax requires each row of the grid template to be written as a quoted string, with repeated names indicating that the named area spans multiple columns or rows. In the shown layout, heading spans the entire top row, menu occupies the left column across lower rows, content spans the central area, right occupies the right-side area, and contact spans the bottom content region. Options B and C are incorrect because named grid-area strings do not belong in grid-template-rows or grid-template-columns; those properties define track sizing, not named layout regions. Option A defines explicit column and row sizes but does not define the semantic named areas shown in the mockup. References/topics: CSS Grid, grid containers, named grid areas, grid-template-areas, responsive page layout.

First blank: < legend > Fundraising Campaign < /legend >

Second blank: < progress id= " donate " value= " 30 " max= " 100 " > < /progress >

Third blank: list= " donateAmount "