IT Specialist INF-306 Exam : HTML5 Application Development

Which value does the following JavaScript code fragment store in the variable num?
var num = localStorage.length;

• A. Maximum length of a character string
• B. Number of bytes available in local storage
• C. Number of key-value pairs in local storage
• D. Potential capacity of local storage

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You need to correctly apply a style rule for screen devices with a width of 480 pixels or less.
Complete the code by selecting the correct option from the drop-down list.

Explanation:
@media screen and (max-width: 480px) {
/* style rules go here */
}
The correct media query is @media screen and (max-width: 480px) {. The requirement says the style rule must apply to screen devices with a width of 480 pixels or less. In CSS media queries, screen identifies the media type, and (max-width: 480px) defines the upper viewport-width limit. This means the enclosed CSS rules apply when the viewport is 480 pixels wide or any smaller value, which is the standard mobile breakpoint behavior. @media screen and (width: 480px) is incorrect because it applies only when the viewport is exactly 480 pixels wide, not below it. @media screen display and (width: 480px) is invalid syntax because display is not used that way in a media query. @media screen-width: 480px is also invalid because it does not follow the required @media media-type and (feature: value) pattern. References/topics: responsive design, CSS media queries, @media, screen media type, max-width, mobile breakpoint styling.

The following output has more text than will fit in the element.

You need to apply CSS to contain the text inside the element ' s border without creating unneeded scrollbars or losing text. Which attribute setting should you use?

• A. overflow:visible;
• B. overflow:auto;
• C. overflow:scroll;
• D. overflow:hidden;

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You want to position a specific element so that it always directly follows the previous element, which is positioned by default, regardless of the viewport characteristics. Which positioning method should you use?

• A. fixed
• B. static
• C. absolute
• D. sticky

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You define the Pet class as follows:
class Pet {
constructor(name, breed) {
this.name = name;
this.breed = breed;
this.show = function() {
var text = " < p > Your pet ' s name is " + name + " . The pet ' s breed is " + breed + " . < /p > " ; return text;
};
}
}
You need to derive a Dog class from the Pet class.
Complete the code by selecting the correct option from each drop-down list.
Note: You will receive partial credit for each correct selection.

Explanation:
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.