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Top 100+ Javascript Objects Interview Questions And Answers - May 31, 2020

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Top 100+ Javascript Objects Interview Questions And Answers

Question 1. What Is Javascript Objects?

Answer :

JavaScript is an Object Oriented Programming (OOP) language. A programming language may be known as item-oriented if it gives four simple competencies to developers −

Encapsulation − the functionality to keep associated facts, whether or not records or methods, collectively in an object.
Aggregation − the functionality to save one item inside any other item.
Inheritance − the functionality of a class to depend on every other elegance (or number of instructions) for some of its homes and methods.
Polymorphism − the capability to write one feature or method that works in a selection of various approaches.
Objects are composed of attributes. If an attribute carries a characteristic, it is considered to be a technique of the object, in any other case the characteristic is taken into consideration a property.

Question 2. What Are Object Properties?

Answer :

Object properties may be any of the 3 primitive records types, or any of the summary records types, consisting of another item. Object properties are normally variables which can be used internally within the object's methods, but also can be globally visible variables which might be used.

The syntax for adding a assets to an object is:

objectName.ObjectProperty = propertyValue;

For instance − The following code receives the report identify the usage of the "identify" belongings of the record item.

Var str = report.Identify;

CSS3 Interview Questions
Question 3. What Is Object Methods?

Answer :

Methods are the features that allow the item do some thing or permit some thing be achieved to it. There is a small difference among a characteristic and a method – at a function is a standalone unit of statements and a technique is connected to an item and may be referenced by means of the this keyword.

Methods are useful for the entirety from showing the contents of the object to the display screen to acting complex mathematical operations on a group of local homes and parameters.

For instance − Following is a easy instance to expose how to use the write() method of report item to write any content material at the record.

Document.Write("This is take a look at");

Question four. What Is User-defined Objects?

Answer :

User-Defined Objects: All consumer-defined gadgets and built-in items are descendants of an item called Object.

The new Operator: The new operator is used to create an example of an item. To create an item, the brand new operator is accompanied with the aid of the constructor technique.

In the following example, the constructor methods are Object(), Array(), and Date(). These constructors are integrated JavaScript features.

Var employee = new Object();
var books = new Array("C++", "Perl", "Java");
var day = new Date("August 15, 1947");

The Object() Constructor: A constructor is a characteristic that creates and initializes an item. JavaScript gives a special constructor feature referred to as Object() to construct the object. The go back cost of the Object() constructor is assigned to a variable.

The variable carries a connection with the new object. The homes assigned to the object aren't variables and are not described with the var key-word.

Example 1: Try the subsequent example; it demonstrates a way to create an Object.

<html>
   <head>
      <title>User-described gadgets</title>
      
      <script type="text/javascript">
         var e book = new Object();   // Create the object
         book.Difficulty = "Perl"; // Assign houses to the object
         ebook.Author  = "Mohtashim";
      </script>
      
   </head>
   
   <body>
   
      <script type="text/javascript">
         record.Write("Book name is : " + e book.Challenge + "<br>");
         file.Write("Book author is : " + e book.Author + "<br>");
      </script>
   
   </body>
</html>

CSS3 Tutorial
Question five. Defining Methods For An Object?

Answer :

The preceding examples reveal how the constructor creates the object and assigns properties. But we want to complete the definition of an object by using assigning techniques to it.

Example: Try the following instance; it suggests a way to upload a function along side an object.

<html>
   <head>
   <title>User-described objects</title>
   
      <script type="text/javascript">
         // Define a characteristic in order to paintings as a technique
         feature addPrice(amount)
            this.Fee = quantity; 
         
         
         characteristic ebook(identify, creator)
            this.Title = title;
            this.Creator  = creator;
            this.AddPrice = addPrice; // Assign that approach as assets.
         
      </script>
      
   </head>
   <body>
   
      <script type="text/javascript">
         var myBook = new e-book("Perl", "Mohtashim");
         myBook.AddPrice(a hundred);
         
         report.Write("Book title is : " + myBook.Title + "<br>");
         report.Write("Book creator is : " + myBook.Writer + "<br>");
         document.Write("Book price is : " + myBook.Charge + "<br>");
      </script>
      
   </body>
</html>

HTML 5 Interview Questions
Question 6. What Is The 'with' Keyword?

Answer :

The ‘with’ keyword is used as a type of shorthand for referencing an object's houses or methods.

The item targeted as an argument to with turns into the default item throughout the block that follows. The residences and strategies for the item can be used without naming the item.

Syntax: The syntax for with item is as follows --

with (item)
   homes used with out the item name and dot


Question 7. What Are The Javascript Native Objects?

Answer :

JavaScript has numerous integrated or native items. These items are reachable anywhere on your software and will paintings the equal way in any browser strolling in any running gadget.

Here is the list of all vital JavaScript Native Objects −

JavaScript Number Object
JavaScript Boolean Object
JavaScript String Object
JavaScript Array Object
JavaScript Date Object
JavaScript Math Object
JavaScript RegExp Object
HTML five Tutorial PHP Interview Questions
Question eight. What Is Javascript Number Object?

Answer :

The Number object represents numerical date, both integers or floating-point numbers. In general, you do no longer need to fear about Number gadgets due to the fact the browser mechanically converts wide variety literals to times of the quantity elegance.

Syntax: The syntax for creating more than a few item is as follows:

var val = new Number(quantity);

In the location of range, if you offer any non-variety argument, then the argument can't be converted into a range of, it returns NaN (Not-a-Number).

Question nine. What Are The Number Properties?

Answer :

Here is a list of each assets and their description.

MAX_VALUE: The biggest feasible value a variety of in JavaScript may have 1.7976931348623157E+308
MIN_VALUE: The smallest possible cost various in JavaScript may have 5E-324
NaN: Equal to a cost that isn't always a variety of.
NEGATIVE_INFINITY: A value that is much less than MIN_VALUE.
POSITIVE_INFINITY: A price this is greater than MAX_VALUE
prototype: A static property of the Number item. Use the prototype property to assign new homes and strategies to the Number item within the cutting-edge record
constructor: Returns the characteristic that created this item's example. By default that is the Number item.
AJAX Interview Questions
Question 10. What Are The Number Methods?

Answer :

The Number item consists of only the default methods that are part of every object's definition.

ToExponential(): Forces a number to show in exponential notation, even though the variety is within the range wherein JavaScript commonly uses general notation.
ToFixed(): Formats a number of with a particular range of digits to the proper of the decimal.
ToLocaleString(): Returns a string price version of the modern quantity in a format which can range in line with a browser's neighborhood settings.
ToPrecision(): Defines what number of total digits (which includes digits to the left and right of the decimal) to show of various.
ToString(): Returns the string representation of the wide variety's cost.
ValueOf(): Returns the wide variety's price.
PHP Tutorial
Question 11. What Is Javascript Boolean Object?

Answer :

The Boolean item represents  values, either "genuine" or "false". If fee parameter is neglected or is 0, -0, null, fake, NaN, undefined, or the empty string (""), the item has an preliminary fee of false.

Syntax: Use the following syntax to create a boolean object.

Var val = new Boolean(value);

CSS Advanced Interview Questions
Question 12. What Are The Boolean Properties?

Answer :

Here is a listing of the houses of Boolean item:

constructor: Returns a connection with the Boolean characteristic that created the item.
Prototype: The prototype assets lets in you to add homes and strategies to an object.
CSS3 Interview Questions
Question thirteen. What Are Boolean Methods?

Answer :

Here is a listing of the techniques of Boolean item and their description.

ToSource(): Returns a string containing the source of the Boolean object; you can use this string to create an equal item.
ToString(): Returns a string of either "genuine" or "false" relying upon the price of the item.
ValueOf(): Returns the primitive cost of the Boolean object.
AJAX Tutorial
Question 14. What Is Javascript Strings Object?

Answer :

The String item helps you to paintings with a chain of characters; it wraps Javascript's string primitive statistics kind with a number of helper techniques.

As JavaScript automatically converts among string primitives and String objects, you may call any of the helper methods of the String object on a string primitive.

Syntax: Use the following syntax to create a String item −

var val = new String(string);

The String parameter is a series of characters that has been nicely encoded.

Question 15. What Are String Properties?

Answer :

Here is a list of the houses of String object and their description.

Constructor: Returns a reference to the String characteristic that created the item.
Length: Returns the length of the string.
Prototype: The prototype belongings allows you to add homes and methods to an item.
Java Abstraction Interview Questions
Question 16. What Are String Methods?

Answer :

Here is a listing of the methods available in String item together with their description.

CharAt(): Returns the man or woman at the specified index.
CharCodeAt(): Returns a range of indicating the Unicode cost of the man or woman at the given index.
Concat(): Combines the text of two strings and returns a new string.
IndexOf(): Returns the index inside the calling String object of the primary occurrence of the specified fee, or -1 if now not found.
LastIndexOf(): Returns the index within the calling String object of the last occurrence of the required cost, or -1 if now not determined.
LocaleCompare(): Returns a number indicating whether a reference string comes earlier than or after or is the same as the given string in sort order.
In shape(): Used to healthy a normal expression towards a string.
Update(): Used to find a suit among a regular expression and a string, and to replace the matched substring with a new substring.
Seek(): Executes the search for a suit between a ordinary expression and a certain string.
Slice(): Extracts a section of a string and returns a brand new string.
Cut up(): Splits a String object into an array of strings by way of isolating the string into substrings.
Substr(): Returns the characters in a string beginning at the specified location through the required number of characters.
Substring(): Returns the characters in a string between  indexes into the string.
ToLocaleLowerCase(): The characters inside a string are transformed to lower case while respecting the contemporary locale.
ToLocaleUpperCase(): The characters within a string are transformed to higher case at the same time as respecting the modern locale.
ToLowerCase(): Returns the calling string fee converted to decrease case.
ToString(): Returns a string representing the required object.
ToUpperCase(): Returns the calling string cost transformed to uppercase.
ValueOf(): Returns the primitive value of the required item.
CSS Advanced Tutorial
Question 17. What Are String Html Wrappers?

Answer :

Here is a list of the techniques that return a copy of the string wrapped inside the precise HTML tag.

Anchor(): Creates an HTML anchor that is used as a hypertext goal.
Massive(): Creates a string to be displayed in a large font as if it were in a tag.
Blink(): Creates a string to blink as if it had been in a tag.
Ambitious(): Creates a string to be displayed as bold as if it were in a tag.
Constant(): Causes a string to be displayed in constant-pitch font as though it have been in a tag
fontcolor(): Causes a string to be displayed within the targeted coloration as if it have been in a tag.
Fontsize(): Causes a string to be displayed in the particular font size as though it were in a tag.
Italics(): Causes a string to be italic, as though it were in an tag.
Hyperlink(): Creates an HTML hypertext link that requests some other URL.
Small(): Causes a string to be displayed in a small font, as though it had been in a tag.
Strike(): Causes a string to be displayed as struck-out text, as if it had been in a tag.
Sub(): Causes a string to be displayed as a subscript, as though it had been in a tag
sup(): Causes a string to be displayed as a superscript, as though it had been in a tag
Javascript Advanced Interview Questions
Question 18. What Is Javascript Arrays Object?

Answer :

The Array object lets you shop a couple of values in a unmarried variable. It stores a fixed-length sequential series of factors of the same type. An array is used to shop a set of facts, however it's far often greater beneficial to consider an array as a set of variables of the same kind.

Syntax: Use the subsequent syntax to create an Array object:

var culmination = new Array( "apple", "orange", "mango" );

The Array parameter is a list of strings or integers. When you specify a single numeric parameter with the Array constructor, you specify the initial period of the array. The most length allowed for an array is 4,294,967,295.

You can create array by using clearly assigning values as follows:

var end result = [ "apple", "orange", "mango" ];

You will use ordinal numbers to get entry to and to set values internal an array as follows.

Culmination[0] is the first element
culmination[1] is the second one element
culmination[2] is the 1/3 detail

HTML 5 Interview Questions
Question 19. What Are Array Properties?

Answer :

Here is a list of the residences of the Array item along side their description.

Constructor: Returns a reference to the array feature that created the object.
Index: The belongings represents the 0-based totally index of the fit within the string
input: This belongings is only found in arrays created with the aid of ordinary expression matches.
Duration: Reflects the variety of elements in an array.
Prototype: The prototype belongings lets in you to feature residences and methods to an object.
Javascript Objects Tutorial
Question 20. What Are Array Methods?

Answer :

Here is a list of the methods of the Array object at the side of their description.

Concat(): Returns a brand new array created from this array joined with other array(s) and/or fee(s).
Each(): Returns proper if every detail in this array satisfies the supplied checking out function.
Clear out(): Creates a new array with all the elements of this array for which the furnished filtering feature returns genuine.
ForEach(): Calls a characteristic for each element inside the array.
IndexOf(): Returns the primary (least) index of an detail in the array identical to the required cost, or -1 if none is found.
Join(): Joins all factors of an array into a string.
LastIndexOf(): Returns the ultimate (finest) index of an element inside the array identical to the specified fee, or -1 if none is discovered.
Map(): Creates a new array with the consequences of calling a furnished feature on each detail in this array.
Pop(): Removes the closing element from an array and returns that detail.
Push(): Adds one or extra elements to the stop of an array and returns the brand new period of the array.
Lessen(): Apply a characteristic simultaneously against two values of the array (from left-to-right) as to reduce it to a single fee.
ReduceRight(): Apply a function simultaneously against  values of the array (from right-to-left) as to reduce it to a unmarried price.
Opposite(): Reverses the order of the elements of an array -- the first becomes the remaining, and the last will become the first.
Shift(): Removes the first detail from an array and returns that detail.
Slice(): Extracts a phase of an array and returns a brand new array.
Some(): Returns real if at the least one element in this array satisfies the supplied checking out characteristic.
ToSource(): Represents the supply code of an item
kind(): Sorts the factors of an array
splice(): Adds and/or removes factors from an array.
ToString(): Returns a string representing the array and its elements.
Unshift(): Adds one or more factors to the front of an array and returns the brand new length of the array.
CakePHP Interview Questions
Question 21. What Is Javascript Date Object?

Answer :

The Date item is a datatype constructed into the JavaScript language. Date gadgets are created with the new Date( ) as proven beneath.

Once a Date item is created, a number of methods allow you to function on it. Most techniques truly allow you to get and set the year, month, day, hour, minute, 2nd, and millisecond fields of the item, the usage of both nearby time or UTC (typical, or GMT) time.

The ECMAScript popular calls for the Date object with a purpose to represent any date and time, to millisecond precision, within one hundred million days earlier than or after 1/1/1970. This is various plus or minus 273,785 years, so JavaScript can represent date and time till the yr 275755.

Syntax: You can use any of the following syntaxes to create a Date object the usage of Date() constructor.

New Date( )
new Date(milliseconds)
new Date(datestring)
new Date(12 months,month,date[,hour,minute,second,millisecond ])

Question 22. What Is Date Properties?

Answer :

Here is a listing of the properties of the Date object along with their description.

Constructor: Specifies the function that creates an item's prototype.
Prototype: The prototype assets lets in you to add houses and techniques to an item.
Javascript Advanced Tutorial
Question 23. What Are Date Methods?

Answer :

Here is a listing of the methods used with Date and their description.

Date(): Returns latest date and time
getDate(): Returns the day of the month for the desired date in step with neighborhood time.
GetDay(): Returns the day of the week for the required date in keeping with neighborhood time.
GetFullYear(): Returns the year of the required date according to neighborhood time.
GetHours(): Returns the hour within the unique date in keeping with neighborhood time.
GetMilliseconds(): Returns the milliseconds within the specified date in keeping with nearby time.
GetMinutes(): Returns the mins in the detailed date according to nearby time.
GetMonth(): Returns the month in the unique date consistent with nearby time.
GetSeconds():Returns the seconds inside the detailed date  in line with neighborhood time.
GetTime(): Returns the numeric fee of the desired date as the range of milliseconds on account that January 1, 1970, 00:00:00 UTC.
GetTimezoneOffset(): Returns the time-region offset in minutes for the current locale.
GetUTCDate(): Returns the day (date) of the month within the distinct date in keeping with everyday time.
GetUTCDay(): Returns the day of the week within the certain date according to widely wide-spread time.
GetUTCFullYear(): Returns the yr within the special date in step with frequent time.
GetUTCHours(): Returns the hours inside the targeted date in keeping with typical time.
GetUTCMilliseconds(): Returns the milliseconds inside the distinct date according to generic time.
GetUTCMinutes(): Returns the mins in the detailed date consistent with conventional time.
GetUTCMonth(): Returns the month inside the certain date in line with regular time.
GetUTCSeconds(): Returns the seconds inside the distinct date in line with accepted time.
GetYear(): Deprecated - Returns the yr inside the targeted date in keeping with neighborhood time. Use getFullYear rather.
SetDate(): Sets the day of the month for a specific date consistent with nearby time.
SetFullYear(): Sets the overall yr for a distinct date in keeping with nearby time.
SetHours(): Sets the hours for a specific date according to neighborhood time.
SetMilliseconds(): Sets the milliseconds for a distinct date in keeping with local time.
SetMinutes(): Sets the mins for a designated date consistent with nearby time.
SetMonth(): Sets the month for a particular date in keeping with neighborhood time.
SetSeconds(): Sets the seconds for a targeted date consistent with neighborhood time.
SetTime(): Sets the Date object to the time represented with the aid of a number of milliseconds seeing that January 1, 1970, 00:00:00 UTC.
SetUTCDate(): Sets the day of the month for a specific date according to popular time.
SetUTCFullYear(): Sets the overall yr for a exact date in keeping with regular time.
SetUTCHours(): Sets the hour for a special date according to usual time.
SetUTCMilliseconds(): Sets the milliseconds for a unique date in step with established time.
SetUTCMinutes(): Sets the mins for a unique date according to standard time.
SetUTCMonth(): Sets the month for a special date in line with regularly occurring time.
SetUTCSeconds(): Sets the seconds for a unique date consistent with normal time.
SetYear(): Deprecated - Sets the year for a precise date in keeping with local time. Use setFullYear rather.
ToDateString(): Returns the "date" part of the Date as a human-readable string.
ToGMTString(): Deprecated - Converts a date to a string, the usage of the Internet GMT conventions. Use toUTCString rather.
ToLocaleDateString(): Returns the "date" portion of the Date as a string, the usage of the present day locale's conventions.
ToLocaleFormat(): Converts a date to a string, the use of a layout string.
ToLocaleString(): Converts a date to a string, the usage of the cutting-edge locale's conventions.
ToLocaleTimeString(): Returns the "time" portion of the Date as a string, the usage of the contemporary locale's conventions.
ToSource(): Returns a string representing the supply for an equal Date item; you may use this value to create a brand new object.
ToString(): Returns a string representing the specified Date item.
ToTimeString(): Returns the "time" part of the Date as a human-readable string.
ToUTCString(): Converts a date to a string, using the accepted time conference.
ValueOf(): Returns the primitive price of a Date item.
CodeIgniter Interview Questions
Question 24. What Are Date Static Methods?

Answer :

In addition to the numerous example techniques listed previously, the Date item additionally defines  static techniques. These techniques are invoked through the Date() constructor itself.

Date.Parse( ): Parses a string illustration of a date and time and returns the inner millisecond representation of that date.

Date.UTC( ): Returns the millisecond illustration of the desired UTC date and time.

PHP Interview Questions
Question 25. What Is Javascript Math Object?

Answer :

The math object presents you residences and methods for mathematical constants and features. Unlike different international objects, Math isn't a constructor. All the houses and methods of Math are static and can be called by way of using Math as an object with out growing it.

Thus, you confer with the consistent pi as Math.PI and also you call the sine characteristic as Math.Sin(x), where x is the method's argument.

Syntax: The syntax to call the houses and strategies of Math are as follows

var pi_val = Math.PI;
var sine_val = Math.Sin(30);

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Question 26. What Are The Math Properties?

Answer :

Here is a list of all the residences of Math and their description.

E : Euler's consistent and the base of natural logarithms, approximately 2.718.
LN2: Natural logarithm of two, approximately 0.693.
LN10: Natural logarithm of 10, approximately 2.302.
LOG2E: Base 2 logarithm of E, about 1.442.
LOG10E: Base 10 logarithm of E, about 0.434.
PI: Ratio of the circumference of a circle to its diameter, about 3.14159.
SQRT1_2: Square root of half of; equivalently, 1 over the rectangular root of 2, approximately zero.707.
SQRT2: Square root of 2, approximately 1.414.
JSON (JavaScript Object Notation) Interview Questions
Question 27. What Are The Math Methods?

Answer :

Here is a list of the strategies associated with Math item and their description

abs(): Returns absolutely the value of a number.
Acos(): Returns the arccosine (in radians) of more than a few.
Asin(): Returns the arcsine (in radians) of a number.
Atan(): Returns the arctangent (in radians) of a number.
Atan2(): Returns the arctangent of the quotient of its arguments.
Ceil(): Returns the smallest integer more than or identical to a variety of.
Cos(): Returns the cosine of a number.
Exp(): Returns EN, in which N is the argument, and E is Euler's constant, the base of the natural logarithm.
Floor(): Returns the biggest integer less than or equal to various.
Log(): Returns the natural logarithm (base E) of various.
Max(): Returns the most important of zero or more numbers.
Min(): Returns the smallest of 0 or greater numbers.
Pow(): Returns base to the exponent power, this is, base exponent.
Random(): Returns a pseudo-random quantity among zero and 1.
Spherical(): Returns the fee of a number of rounded to the nearest integer.
Sin(): Returns the sine of a number of.
Sqrt(): Returns the rectangular root of a range of.
Tan(): Returns the tangent of a range of.
ToSource(): Returns the string "Math".
AJAX Interview Questions
Question 28. What Are Regular Expressions And Regexp Object?

Answer :

A everyday expression is an object that describes a sample of characters.

The JavaScript RegExp class represents normal expressions, and each String and RegExp outline methods that use normal expressions to carry out powerful pattern-matching and search-and-update functions on textual content.

Syntax: A ordinary expression may be defined with the RegExp () constructor, as follows −

var sample = new RegExp(pattern, attributes);
or certainly
var sample = /sample/attributes;

Here is the description of the parameters:

sample − A string that specifies the pattern of the regular expression or another regular expression.
Attributes − An optional string containing any of the "g", "i", and "m" attributes that explain global, case-insensitive, and multiline fits, respectively.
CodeIgniter Tutorial
Question 29. What Are Brackets?

Answer :

Brackets ([]) have a unique meaning while used inside the context of ordinary expressions. They are used to find a variety of characters.

[...]: Any one character among the brackets.
[^...]: Any one character not between the brackets.
[0-9]: It fits any decimal digit from zero thru 9.
[a-z]: It matches any person from lowercase a through lowercase z.
[A-Z]: It matches any individual from uppercase A thru uppercase Z.
[a-Z]: It matches any character from lowercase a through uppercase Z.
The tiers proven above are popular; you may additionally use the variety [0-3] to suit any decimal digit starting from zero thru 3, or the variety [b-v] to healthy any lowercase man or woman ranging from b thru v.

Advanced jQuery Interview Questions
Question 30. What Are Quantifiers?

Answer :

The frequency or function of bracketed individual sequences and single characters can be denoted by using a special individual. Each special individual has a selected connotation. The +, *, ?, and $ flags all observe a person collection.

P+: It suits any string containing one or greater p's.
P*: It matches any string containing zero or more p's.
P?: It fits any string containing at maximum one p.
PN: It matches any string containing a chain of N p's
p2,3: It fits any string containing a series of  or 3 p's.
P2, : It fits any string containing a sequence of at least two p's.
P$: It fits any string with p on the stop of it.
^p: It matches any string with p at the beginning of it.




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