Questions and Answers of JavaScript

Which of the following type values for the input element does not enable you to provide users with a limited set of choices?a. Radiob. Emailc. Checkboxd. Range
What is the constraint validation API?
What property do you check to determine if a text input box contains user input?
What value of the selectedIndex property of a select object corresponds to no selection?a. -1b. 0c. 1d. False
What is one drawback of using browser-based validation?
What built-in JavaScript function do you use to test whether a value is not a number?
To simulate the behavior of placeholder text in older browsers, you can instead set the value of the _______ property.a. Srcb. Altc. Titled. Value
Which event do you use to call a function when a user selects a field or moves the insertion point into a field?a. Blurb. Focusc. Inputd. Forminput
Which event do you use to call a function when a field is no longer selected, or a user moves the insertion point to a different field?a. Blurb. Focusc. Clickd. Forminput
What do you assign to the value property of a text input box to remove its content?a. Falseb. Truec. ""d. Null
Which of the following attributes triggers browser-based validation in modern browsers?a. Maxb. Titlec. Altd. Src
Which of the following attributes determines whether a check box or option button is selected?a. Checkedb. Defaultcheckedc. Selectedd. Focus
Which of the following input type values triggers browser-based validation in modern browsers?a. Passwordb. Textc. Radiod. Number
Which of the following properties has a value of true when a user has left a required field blank?a. Requiredb. Valuemissingc. Patternmismatchd. Typemismatch
Which of the following attributes for form child elements would you use for a field that must have a value before the form can be submitted?a. Novalidateb. Minc. Requiredd. Max
What method do you use to disable the default behavior for an event?a. preventdefault()b. checkValidity()c. select()d. getElementById()
For any fields that require numeric values, you can use JavaScript’s built-in ________ function to determine whether the user actually entered a number.a. Value()b. Integer()c. Isnumber()d. Isnan()
Explain how to transfer the contents of one field to another field.
What is the purpose of the novalidate attribute?
Explain how the validity object of the constraint validation API is used for checking the validity of form data.
Explain how to check if any option button in a set is selected.
Explain how to check if a user’s entry is a number.
In object-oriented programming, a(n) __________ is a template, or blueprint, that serves as the basis for new objects.a. Instanceb. Objectc. Methodd. Class
What is object-oriented programming? What is an object?
What code creates a dateToday variable and assigns the current date and time as its value?
What statement would you use to create a new empty object with the name manifest using an object literal?
In object-oriented programming, a(n) __________ is an object that has been created from an existing template.a. Instanceb. Propertyc. Methodd. Class
Name at least two built-in JavaScript classes.
Which method of the Number class do you use to convert a number to a string that is formatted with local numeric formatting style?
What statement would you use to add a property named itemNum to the manifest object, and assign the property a numeric value of 1501?
Which of the following Date class constructors creates a Date object that contains the current date and time from the local computer?a. Date()b. Date(milliseconds)c. Date(date_string)d. Date(year,
What is the result of applying the floor() method of the Math class to a numeric value?
What single statement would you use to create a new empty object with the name manifest that includes a property named itemNum with a value of 1501?
Which of the following parts of a date value are stored in a Date object using numeric representations, starting with zero, similar to an array?a. Day of the monthb. Monthc. Yeard. AM/PM
Which Number method converts a number to a string using a specified number of decimal places?a. toFixed()b. toLocaleString()c. toString()d. valueOf()
Which Number method converts a number to a string that is formatted with local numeric formatting style?a. toFixed()b. toLocaleString()c. toString()d. valueOf()
Which is the primary reason for using any of the “to” methods of the Number class?a. To convert a number for use in calculationsb. To format a datec. To perform calculationsd. To convert a number
Which method of the Math class rounds a value to the next lowest integer?a. floor()b. max()c. min()d. round()
What is the correct syntax for rounding the number 39.75 to the nearest integer?a. new Math = round(39.75);b. var mathCalc = new Math(round(39.75));c. Math.round(39.75);d. round(39.75);
Which of the following statements creates an empty object with the name registry?a. var registry;b. var registry = {};c. var registry = "";d. var registry = [];
Which of the following statements adds a new property named squareFeet to an object named RealEstate?a. var RealEstate.squareFeet;b. RealEstate.squareFeet = "";c. var squareFeed.RealEstate;d.
A property whose value is itself an object is known as a(n) __________.a. Sub-propertyb. Instancec. Constructord. Sub-object
Given the object definition13.1which statement references the value of the founder property using an associative array?a. founderb. members.founderc. members["founder"]d. members[0] var
Which statement declares a method named __________ and sets its value to the existing calculateTotal() function?a. calcTotal: calculateTotalb. calcTotal: calculateTotal()c. calcTotal:
The built-in property that specifies the constructor from which an object was extended is called the __________ property.a. Defaultb. Originationc. Prototyped. Source
Explain the principle of information hiding. What does the term “black box” refer to?
Explain why programmers use the terms “variable” and “object” interchangeably.
Explain why JavaScript is not a true object-oriented programming language.
Explain how to assign a new property to a custom object.
Explain when you would use an object literal and when you would create a constructor function.
What string property returns the number of characters in a string?
How do you use the test() method of the RegExp object to check a string against a regular expression?
When you use the slice() method, you provide two values as arguments. Explain what these two values signify.
Which method do you use to convert a string to an array? Which object is this a method of?
Extracting characters or substrings from a larger text string is known as __________.a. Parsingb. Compilingc. Renderingd. Stripping
Explain which values you provide for the two arguments of the substring() and slice() methods.
What is an anchor in a regular expression? What two characters are used as anchors?
What is the difference between the shift() and unshift() methods?
What is the difference between the toString() and toLocaleString() methods of the String object?
What is the property of the String class that returns the number of characters in a string?a. Charsb. Sizec. Widthd. Length
In the expres sion var result = sourceString.localeCompare(compareString), what are the possible return values and what does each mean?
What characters surround a subexpression?
How do the pop() and push() methods work?
What is JSON? What is it used for?
Regular expression patterns in JavaScript must begin and end with which characters?a. { }b. / /c. ( )d. [ ]
What characters surround a character class?
Which of the following is a method of the RegExp class for working with regular expressions?a. search()b. subexpression()c. test()d. class()
Which metacharacter in a regular expression represents any single character?a. $b. ^c. \d. .
Which metacharacter(s) in a regular expression represent characters to exclude?a. ()b. []c. [^]d. -
To match any metacharacter as a literal value in a regular expression, you must _________.a. Enclose the character in brackets ([ ])b. Enclose the character in parentheses (( ))c. Precede the
Which of the following expressions would return false?a. /^1./.test("1.10")b. /^1\./.test("1.10")c. /1.$/.test("1.10")d. /1\.$/.test("1.10")
Which of the following quantifiers specifies that the preceding character repeat at least 2 times?a. {2}b. {2,}c. +d. ?
Which of the following characters do you use to create a subexpression?a. [ ]b. / /c. ( )d. { }
Which of the following expressions represents numeric characters?a. \sb. \bc. \dd. \D
Which method of the Array class removes the last element from the end of an array?a. pop()b. push()c. shift()d. unshift()
What array would result from the following statement? [white, silver, blue].splice(1, 0, "gray");a. [gray, silver, blue]b. [white, gray, blue]c. [white, gray, silver, blue]d. [gray, white,
The JSON.parse() method converts a value to which data type?a. Objectb. Stringc. Arrayd. Number
After running the statementswhat is the value of the media variable, and why? var media "dvd", label media.toUpperCase ();
What is the difference between the indexOf() and lastIndexOf() methods?
Explain why you would specify negative argument values for the slice() method.
Does the expression "a" < "A" evaluate to true or false? Why?
What is the difference between the shift() and unshift() methods of the Array class?
What does W3C stand for? What does the organization do?
What does the middle tier do in a three-tier architecture?
Why should you end every JavaScript statement with a semicolon?
What is the difference between declaring and initializing a variable?
How do you incorporate the contents of a JavaScript source file into an HTML document?
What organization oversees the development of web technology standards?a. U.S Department of Defenseb. World Wide Web Consortiumc. Stanford Universityd. United Nations
What are the codes in an HTML document called? What function do they serve?
What is ECMAScript? Why was is created?
How do you create a single-line comment in JavaScript? How do you create a multiline comment in JavaScript?
How do you change the value of a variable?
The markup language originally developed to create web pages and still in use today is called __________.a. HTMLb. SGMLc. XMLd. CSS
What is an event handler for?
__________ is a separate, complementary language to HTML that was developed for specifying the appearance of web page elements.a. XHTMLb. SGMLc. XMLd. CSS
Elements that do not require a closing tag are called __________ elements.a. Independentb. Emptyc. Permanentd. Constant
What is the root element of an HTML document?a. Headb. Bodyc. Htmld. Script
A system consisting of a client and a server is known as a __________.a. Mainframe topologyb. Double-system architecturec. Two-tier systemd. Wide area network
What is usually the primary role of a client?a. Locating records that match a requestb. Heavy processing, such as calculationsc. Data storaged. The presentation of an interface to the user
Which of the following functions does the processing tier not handle in a three-tier client/server system?a. Processing and calculationsb. Reading and writing of information to the data storage

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