What are Objects in JavaScript? How to Use them?

What are Objects in JavaScript? How to Use them? Objects in JavaScript are collections of properties, each of which is defined as a pair of keys and values. Real-world entities or more abstract data structures can be represented by objects. Any kind of data, including another object, an array, a function, or simple values like strings and numbers, can be the value of each property key, which is a string (or symbol). Data is stored, manipulated, and passed using objects, which are essential to JavaScript programming. The new Object() constructor or curly braces {} are used to generate them. You can use bracket notation (e.g., objectName[‘propertyName’]) or dot notation (e.g., objectName.propertyName) to access or edit an object’s properties. Moreover, object-oriented programming paradigms can be used in JavaScript development since objects in the language can contain methods—that is, functions that are kept as attributes.

Exploring Objects in JavaScript:

JavaScript object exploration requires a thorough comprehension of properties and methods. Here’s a thorough analysis of both, complete with examples to show how to utilize them.

Properties of an Object:

Properties are key-value pairs that are used to hold information about an object. They provide the object’s state definition.

Defining Properties:

At Creation: The object literal itself allows for the direct definition of properties.

Adding Properties Later: After an object is created, it is possible to add properties to it.

Accessing Properties:

Dot Notation: The most often used method of property access.

When property names are dynamic or invalid identifiers, bracket notation is helpful.

Modifying Properties: By utilizing dot or bracket notation, you can alter a property’s value.

Delete Properties: The delete operator can be used to get rid of properties.

Methods of an Object:

Properties of an object store functions, which are called methods. They describe how an object behaves.

Defining Methods:

Although their values are functions, methods are added in the same manner as other properties.

Using this Keyword: The method’s object is referenced when a method uses this keyword. This enables methods to communicate with other methods and the characteristics of the object.

Built-in Object Methods:

There are numerous built-in ways to handle objects in JavaScript.

Object.keys(obj): Gives back an array containing the property names (keys) of the object.

Property values of the object are returned as an array by calling Object.values(obj).

Object.entries(obj): Provides an array containing all of the key-value pairs in the object.

Property copies from source objects to a target object are accomplished using the Object.assign(target,…sources) method.

When an object is frozen, it becomes immutable (Object.freeze(obj)).

Object.seal(obj): Seals the object, allowing changes to be made to its current properties but prohibiting the addition of new ones.

JavaScript objects play a crucial role in organizing and handling data. The behavior of an object is defined by its methods, and its properties record its state. Using objects to construct dynamic and intricate JavaScript applications is simple if you know how to define, access, edit, and use attributes and methods.

Exploring the Standard/Built-in JavaScript Objects:

The built-in JavaScript standard objects offer a comprehensive collection of capabilities for working with data, modifying the DOM, and communicating with the browser. Essential functions for data management and mathematical calculations are provided by core objects such as objects, arrays, strings, numbers, and Math. Dynamic interaction between web page elements is made easier by DOM objects like documents and elements. Browser components such as Windows and Console offer methods for timing operations, alarm display, and debugging. Programming JavaScript effectively and potently requires an understanding of and utilization of these built-in components.

The String Object:

The String object is one built-in JavaScript object that lets you work with character sequences. Text can be stored and altered via strings. JavaScript strings are immutable, meaning they cannot be altered once they are produced. However, new strings can be created by performing operations on already-made strings.

PropertyDescription
constructorreturns the function that is used to build the string object prototype.
lengthreturns a string’s length
prototypegives an object additional methods and properties.
Table 1 – Properties of the String Object in JavaScript
Method Description
charAt()returns the character in the designated index.
charCodeAt()returns the character’s Unicode equivalent for the given index.
concat()connects two strings, returning the joint string in return.
fromCharCode()translates Unicode to character
indexOf()returns the string’s position where the given character appears for the first time.
lastindexof()provides the location of the last instance of a given value in a string.
match()finds results in a string when a regular expression is used, and returns those matches.
quote()utilizes JavaScript to write quotes
replace()finds the matching substring in a string by matching it with a regular expression, then replaces it via the new substring.
search()finds the position of a match when it compares a regular expression to a string.
slice()a portion of a string is returned as a new string.
split()creates substrings from a string
substr()retrieves a string’s characters for the given number of characters, starting at the given start index.
substring()brings back characters from a string between two given indices.
toLowerCase()changes the value of a string to a lowercase letter.
toSource()returns an object literal that corresponds to the given object.
toString()returns a string that describes the specified item.
toUpperCase()produces an uppercase letter from a string.
valueOf()delivers a string object’s primitive value back.
Table 2 – Methods of the String Object in JavaScript
MethodDescription
anchor()creates an anchor
big()shows a string with a big font
blink()makes the string to blink
bold()makes the string bold
fixed()shows the string by using fixed pitch font, such as Courier New or Book Antiqua
fontcolor()shows the string with the specified color
fontsize()shows the string with the specified size
italica()shows the string in italics
link()shows the string as a hypertext link
small()shows a string with a small font
strike()shows the string with a struck-out text
sub()shows the string as a subscript text
sup()shows the string as a superscript text
Table 3 – Wrapper Methods that Return a String Object in JavaScript
List of OperatorsDescription
!=the not equal operation is represented
<the less-than operation is represented
>the greater than operation is represented
+the concatenate operation is represented
<=the less than or equal to operation is represented
>=the greater than or equal to operation is represented
+=the concatenate assignment operation is represented
==the equal operation is represented
Table 4 – List of Comparison Operators in JavaScript

JavaScript’s String object offers a plethora of properties and methods for effective text manipulation. Working with textual data in JavaScript is made simple by the built-in string functions, which may be used for splitting, merging, searching, and formatting strings.

The RegExp Object:

For text manipulation and pattern matching, JavaScript’s RegExp (regular expression) object is an incredibly useful tool. Patterns called regular expressions are used to match character combinations in strings. The RegExp object offers functions like exec(), which yields an array of matched results, and test(), which determines whether a pattern is present in a text. Regular expressions can be created with the RegExp constructor (new RegExp(‘pattern’, ‘flags’)) or with literals (/pattern/flags). Replacing text, searching, and validating input are common applications. Regular expressions are flexible for a variety of string operations because they support flags like i for case-insensitive matching, g for global matching, and m for multi-line matching.

Following are the three types of flags in javascript:

  • Global (g): The g flag designates that every potential match in a string should be checked against the regular expression. The regular expression will only check for the first match if this flag is absent.
  • Case-insensitive (i): The regular expression is made case-insensitive by the i flag, which means that it will match letters in any case (upper or lower).
  • Multi-line (m): The input string is treated as numerous lines by the m flag. The beginning and ending of every line, not simply the start and finish of the string, will be matched by the ^ and $ anchors.
PatternDescription
Pattern delimiters:
(pattern), (?:pattern)matches the entire contained pattern
(pattern) retains the match
(?:pattern) does not retain the match
Lookaheads:
(?=pattern), (?!pattern)(?=pattern) matches only if the given condition is satisfied
(?!pattern) matches only if the given condition is not satisfied
Character Escapes:
/f, /r, /n, /t, /v, /0, [/b], /s, /S, /w.
/W. /d, /D, /b, /B, /cX, /xhh, /uhhhh
/f matches form-feed.
/r matches carriage return.
/n matched linefeed.
/t matches the horizontal tab.
/v matches the vertical tab.
/0 matches the NUL character.
[/b] matches backspace.
/s matches whitespace.
/Smatches anything but a whitespace.
/w matches any alphanumerical character (word characters) including underscore.
/W matches any non-word characters.
/d matches any digit.
/D matches any non-digit.
/b matches a word boundary.
/B matches a non-word boundary.
/cX matches a control character, example g: /cd matches control-d.
/xhh matches the character with two characters of hexadecimal code hh.
/uhhhh matches the Unicode character with four characters of hexadecimal code hhhh.
Character Sets:
[characters], [∧characters][characters] matches all the contained characters
[∧characters] matches all but the contained characters
Table 5 – Patterns Used in RegExp Object in JavaScript
QuantifierDescription
n+indicates a string that contains at least one n
n*indicates a string that contains zero or more occurrences of n
n?indicates a string that contains zero or one occurrence of n
n(a)indicates a string that contains n, several times
n(a,b)indicates a string that contains n, a to b number of times
n(a,)indicates a string that contains n, a, or more number of times
n$indicates a string that ends with n
∧nindicates a string that begins with n
?=nindicates a string that is followed by a specific string n
?!nindicates a string that is not followed by a specific string n
Table 6 – List of Quantifiers of the RegExp Object in JavaScript
PropertyDescription
globalindicates that the g modifier is set
ignoreCaseindicates that the I modifier is set
lastIndexindicates the index to start the next match
multilineindicates that the m modifier is set
sourceindicates the text of the RegExp pattern
Table 7 – List of Properties of the RegExp Object in JavaScript
MethodDescription
compile()complies the RegExp object
exec()tests for a match in a string and returns a result array
test()tests for a match in a string and returns true or false
Table 8 – List of Methods of the RegExp Object in JavaScript

The Boolean Object:

Wrapping around the basic boolean data type is the JavaScript Boolean object. Either true or false is what it stands for. The Boolean object offers a mechanism to work with primitive boolean values as objects, which might be helpful in some situations, even if these values are just true or false.

Creating Boolean Values:

Boolean Literals: The literals true and false can be used to create boolean values.

Boolean Constructor: The Boolean constructor can also be used to produce Boolean values.

Boolean Object vs. Boolean Primitive: Understanding the distinction between the two types of data structures is critical. Whereas boolean primitives are just true or false, boolean objects are instances of the Boolean class.

Truthy and Falsy Values:

JavaScript’s Boolean constructor and the!! (double negation) operator can be used to turn any value into a boolean. Convertible values are said to as “truthy,” while converging values are referred to as “falsy.”

Falsy Values: The following values are considered falsy:

  • false
  • 0
  • -0
  • 0n (BigInt zero)
  • “” (empty string)
  • null
  • undefined
  • NaN

True Values: Any value that isn’t marked as false is taken to be true.

Properties and Methods of the Boolean Object:

Although the Boolean object itself has few properties and methods of its own, it inherits methods from Object.prototype.

Properties:  Boolean.prototype: This is the Boolean constructor prototype.

Methods: The toString() method returns a string that represents the given Boolean object.

valueOf(): Provides the specified Boolean object’s primitive value.

PropertyDescription
constructorreturns the function that produced the boolean object’s prototype.
prototypeenables you to provide an object with more properties and methods
MethodDescription
toString()returns the string after converting the boolean value to a string.
valueOf()returns a boolean object’s primitive value.
Table 9 – Properties and Methods of the Boolean Object in JavaScript

Usage in Conditional Statements: To regulate how a program flows, conditional statements frequently use booleans.

Implicit Conversion to Boolean: In situations where a boolean is needed, including conditional statements and logical operators, JavaScript automatically converts values to boolean.

In JavaScript, primitive boolean values can be wrapped into an object using the Boolean object. Although this might be helpful in some situations, because of their ease of use and efficiency, primitive booleans are usually utilized more frequently. JavaScript programmers must comprehend the difference between truthy and falsy values and how to transform them to boolean.

The Number Object:

JavaScript’s Number object provides properties and methods for numerical operations, essentially acting as a wrapper for the primitive number data type. It enables you to work with constants, parse numbers, and convert integers to strings, among other things. Key methods include Number.isFinite() to check if a value is finite, Number.isInteger() to check if it’s an integer, Number.parseFloat() and Number.parseInt() for parsing strings into numbers, and toFixed() for formatting numbers to a fixed number of decimal places. Properties like Number.MAX_VALUE and Number.MIN_VALUE represent the largest and smallest possible numeric values in JavaScript, respectively. For manipulating numerical data and carrying out mathematical operations, the {Number} object is necessary.

PropertyDescription
constructorcontains the value of the object’s constructor function.
MAX VALUEreturns a maximum number that JavaScript can handle
MIN VALUEreturns a minimal number that JavaScript can handle
NEGATIVE INFINITYreturns the infinite value of negativity
POSITIVE INFINITYreturns the concept of infinite
prototypeadds methods and properties to the number of objects
Table 10 -Properties of the Number Objects in JavaScript
MethodDescription
toExponential (x)makes an exponential notation out of a number
toFixed (x)After the decimal, round up the number to x digits.
toPrecision (x)rounds up a number to a length of x digits
toString ()provides a string value for the number object
valueOf ()provides a primitive value for the number of objects
Table 11 – Methods of the Number Objects in JavaScript

The Array Object:

For storing and manipulating collections of elements, JavaScript’s built-in Array object is a strong tool. Numbers, texts, objects, and other arrays are just a few of the values that can be stored in arrays. To add elements to the end, pop() removes the final element, shift() adds elements at the beginning, and unshift() removes elements at the end are some of the important methods of the Array object. Aside from altering items, filtering elements that match specific criteria, accumulating values using reduce(), and running a function on each element individually using forEach() are other helpful ways. In addition, an array’s length property shows how many elements it contains. To work with lists of data and execute various operations on collections, one must have access to the Array object.

Array Literals: Using array literals is the most popular method for creating arrays.

Array Constructor: The Array constructor is another tool for creating arrays

PropertyDescription
constructorcontains the value of the constructor function that has created the object
lengthmaintains the array’s element count.
prototypeadds properties and methods to the array object
Table 12 – List of Properties of the Array Object in JavaScript
MethodDescription
concat()connects two or more arrays, then gives back the combined array.
join()combines an array’s elements into a string.
pop()removes and returns the final element from an array.
push()returns the length of the new array and adds a new element as the final element.
reverse()flips the list of elements in an array’s order
shift()removes the first element of an array and returns that element
slice()returns a part of an array that has been selected as a new array.
sort()The elements of an array are sorted.
splice()adds or deletes an array’s elements
tostring()returns a string after converting an array to a string.
unshift()gives the updated length after adding new elements to an array.
valueof()returns an array object’s primitive value.
Table 13 – List of Methods of the Array Object in JavaScript

The Math Object:

In JavaScript, the built-in Math object offers several properties and methods for carrying out mathematical calculations. It contains constants such as Math.E for Euler’s number and Math.PI for the value of π. Math.abs() converts data to absolute values; Math.ceil() and Math.floor() rounds numbers up or down; Math.max() and Math.min() finds the highest or smallest value among arguments; Math.random() generates random numbers; and Math.sqrt() computes square roots. These are some of the important functions. Since there is no constructor on the Math object, all of its methods and properties are static and are used straight out of Math. JavaScript mathematical computations require this object.

PropertyDescription
Econtains the Euler’s number, which is roughly equivalent to 2.718.
LN2contains the natural logarithm of 2, which is about equivalent to 0.693.
LN10contains the natural logarithm of 10, which is about equivalent to 2.302
LOG2Econtains the base-2 logarithm of E, which is about equivalent to 1.442.
LOG10Econtains the base-10 logarithm of E, which is about equivalent to 0.434.
PIholds the PI numerical value, which is approximately 3.142.
SQRT1_2contains the 1/2 square root, which has an approximate value of 0.707.
SQRT2contains the square root of two, which is about equivalent to 1.414.
Table 14 – Properties of the Math Object in JavaScript
MethodDescription
abs (x)gives the absolute value of x
acos (x)gives arccosine (in radian) of x
asin (x)gives arcsine (in radian) of x
atan (x)gives the arctangent of x with numeric value between -PI/2 and PI/2 radians
atan2 (y,x)gives the arctangent of the quotient on dividing y and x
ceil (x)rounds up x to the nearest biggest integer
cos (x)gives cosine value of x
exp (x)gives the value of ex
floor (x)rounds up x to the nearest smaller integer
log (x)gives the natural logarithmic value of x
max (x, y, z,…, n)gives the highest number from the given list
min (x, y, z,…, n)gives the lowest number from the given list
pow (x, y)gives x to the power of y
random ()gives a random number between 0 and 1
round (x)rounds up x to the nearest integer
sin (x)gives the sine value of x
sqrt (x)gives the square root of x
tan (x)gives the tangent value of x
Table 15 – Methods of the Math Object in JavaScript

The Date Object:

In JavaScript, the Date object is an inbuilt object that facilitates creating, modifying, and formatting dates and times. It has functions to parse date strings and format dates in addition to retrieving and setting the year, month, day, hour, minute, second, and millisecond of a date object. For obtaining individual date components, important methods include getDate(), getMonth(), getFullYear(), getHours(), getMinutes(), and getSeconds(). In addition, the Date object is capable of date arithmetic operations like adding and subtracting time intervals. In JavaScript applications, it is a crucial utility for managing the date and time.

PropertyDescription
constructorcontains the value of the constructor function that has created the object
prototypeadds methods and properties to the date object
Table 16 – Properties of the Date Object in JavaScript
MethodsDescription
getDate ()returns the month’s day, which varies from 1 to 31.
getDay ()gives back the day of the week’s numerical equivalent, which runs from 0 to 6, with Monday represented by 0 and Sunday by 6.
getFullYear ()provides the year’s numerical equivalent in four digits.
getHours ()gives back the hours between 0 and 23.
getMilliseconds ()gives back the milliseconds, which have a range of 0 to 999.
getMinutes ()gives back minutes between 0 and 59.
getMonth ()gives back the month’s numerical equivalent, which goes from 0 to 11.
getSeconds ()gives back a range of seconds, from 0 to 59.
getTime ()provides the milliseconds since January 1, 1970, at midnight.
getTimezoneOffset ()provides the time difference (in minutes) between the local time and Greenwich Mean Time (GMT).
getUTCDate ()returns, in accordance with universal time, the day of the month (from 1 to 31).
getUTCDay ()provides the day of the week’s numerical equivalent (ranging from 0 to 6) under the universal time
getUTCFullYear ()returns the year using the universal time format in four digits.
getUTCHours ()returns the hours in accordance with the universal time, which spans from 0 to 23.
getUTCMilliseconds ()returns the milliseconds according to the universal time, which has a range of 0 to 999.
getUTCMinutes ()returns the minutes in accordance with the universal time, which spans from 0 to 59.
getUTCMonth ()gives back the month’s numerical equivalent (which goes from 1 to 31) in accordance with the universal time
getUTCSeconds ()provides the seconds in accordance with the universal time, which spans from 0 to 59.
parse ()parses a date string and yields the milliseconds since January 1, 1970’s midnight.
setDate ()determines a month’s first day, which spans from 1 to 31.
setFullYear ()displays the year in four numbers.
setHours ()establishes a range of hours from 0 to 23.
setMilliseconds ()defines the milliseconds, which have a range of 0 to 999.
setMinutes ()decides the minutes, which have a range of 0 to 59.
setMonth ()specifies the month’s numerical equivalent, which is between 0 and 11.
setSeconds ()determines the seconds, which are between 0 and 59.
setTime ()determines the time and day by dividing the specified milliseconds by the midnight of January 1, 1970.
setUTCDate ()determines the day of the month based on the universal time, which spans from 1 to 31.
setUTCFullYear ()sets the year using the universal time format with four digits.
setUTCHours ()determines the hours, which are between 0 and 23 according to the universal time
setUTCMilliseconds ()determines the milliseconds, which have a range of 0 to 999 according to the universal time
setUTCMinutes ()sets the minutes according to the universal time, which has a range of 0 to 59.
setUTCMonth ()determines the month’s numerical equivalent, which runs from 0 to 11, in accordance with the universal time
setUTCSeconds ()sets the seconds according to the universal time, which has a range of 0 to 59.
toDateString ()dates are converted to a string
toLocalDateString ()changes a date to a string in accordance with regional customs
toLocalTimeString ()transforms time to a string in accordance with regional custom
toLocalString ()uses the local convention to turn the date object into a string.
toString ()Creates a string from the date object
toTimeString ()transforms time as a string.
toUTCString ()as per the universal time, transforms the date object into a string.
UTC ()retains the milliseconds since January 1, 1970, at midnight, in accordance with the universal time
valueOf ()sends back the date object’s primitive value
Table 17 – Methods of the Date Object in JavaScript

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