JavaScript Built in Objects
JavaScript has several builtin or core language objects. These builtin objects are available regardless of window content and operate independently of whatever page your browser has loaded.
Array Object
 Multiple values are stored in a single variable using the Array object.
 In JavaScript, an array can hold different types of data types in a single slot, which implies that an array can have a string, a number or an object in a single slot.
 An Array object can be created by using following ways:
Using the Array Constructor:
To create empty array when don’t know the exact number of elements to be inserted in an array
var arrayname = new Array();
To create an array of given size
var arrayname = new Array(size);
To create an array with given elements
var arrayname = new Array(“element 1”,”element 2”,……..,”element n”);
Using the Array Literal Notation:
To create empty array
var arrayname =[ ];
To create an array when elements are given
var arrayname =[“element 1”,”element 2”,……..,”element n”];

Properties of the Array object
 Length – Returns the number of elements in the array.
 Constructor – Returns the function that created the Array object.
 Prototype – Add properties and methods to an object.

Methods of the Array object
 reverse() – Reverses the array elements
 concat() – Joins two or more arrays
 sort() – Sort the elements of an array
 push() – Appends one or more elements at the end of an array
 pop() – Removes and returns the last element
 shift() – Removes and returns the first element
 unshift(), join(), indexOf(), lastIndexOf(), slice(startindex, endindex) are some of the methods used in Array object.
Boolean Object
 The Boolean object is wrapper class and member of global objects.
 It is used to convert a nonBoolean value to a Boolean value (true or false).
 If the Boolean object has no initial value or if it is 0, 0, null, “”, false, undefined, or NaN, the object is set to false. Otherwise it is true (even with the string “false”)!
 Boolean object can be created by using following ways:
Using Boolean Literal Notation: var bool = true;
Using Boolean Object as Function: var bool = Boolean(true);
Using Testable Expressions: if(true) {………….}
 Properties of the Boolean object
 Constructor – Returns the function that created the Boolean object.
 Prototype – Add properties and methods to an object.
 Methods of the Boolean object
 toSource() – Returns a string containing the source of the Boolean object; you can use this string to create an equivalent object.
 toString() – Returns a string of either “true” or “false” depending upon the value of the object.
 valueOf() – Returns the primitive value of the Boolean object
Date Object
 At times when user need to access the current date and time and also past and future date and times. JavaScript provides support for working with dates and time through the Date object.
 The Date object provides a systemindependent abstraction of dates and times.
 Date object can be created as :
var today = new Date( );
 Dates may be constructed from a year, month, day of the month, hour, minute, and second, and those six components, as well as the day of the week, may be extracted from a date.
 Dates may also be compared and converted to a readable string form. A Date is represented to a precision of one millisecond.
 Properties of Date object
 Constructor – Returns the function that created the Date object.
 Prototype – Add properties and methods to an object.
 Methods of Date object
 Date() – Returns today’s date and time
 getDate() – Returns the day of the month for the specified date
 getDay() – Returns the day of the week for the specified date
 getFullYear() – Returns the year of the specified date
 getHours() – Returns the hour in the specified date according to local time.
 getMilliseconds() – Returns the milliseconds in the specified date according to local time.
 getMinute(), getMonth(), getTime(), getTimezoneOffset(), setDate(), setFullYear(), setHours(), setMilliseconds(), setMinutes(), setMonth(), setSeconds(), setTime() are some of the methods used in Date object.
Math Object
 The Math object is used to perform simple and complex arithmetic operations.
 The Math object provides a number of properties and methods to work with Number values
 The Math object does not have any constructors. All of its methods and properties are static; that is, they are member functions of the Math object itself. There is no way to create an instance of the Math object.
 Properties of Math object
 PI – The value of Pi
 E – The base of natural logarithm e
 LN2 – Natural logarithm of 2
 LN10 – Natural logarithm of 10
 LOG2E – Base 2 logarithm of e
 LOG10E – Base 10 logarithm of e
 SQRT2 – Square root of 2
 SQRT1_2 – Square root of ½
 Methods of Math object
 max(a,b) – Returns largest of a and b
 min(a,b) – Returns least of a and b
 round(a) – Returns nearest integer
 ceil(a) – Rounds up. Returns the smallest integer greater than or equal to a
 floor(a) – Rounds down. Returns the largest integer smaller than or equal to a
 exp(a) – Returns ea
 pow(a,b) – Returns ab
 abs(a) – Returns absolute value of a
 random() – Returns a pseudo random number between 0 and 1
 sqrt(a) – Returns square root of a
 sin(a) – Returns sin of a (a is in radians)
 cos(a) – Returns cos of a (a is in radians)
Number Object
 The Number objects represents numerical date, either integers or floatingpoint numbers.
 A Number objects are created using the Number() constructor
var num = new number(value);
 Properties of Number object
 Constructor – Returns the function that created the Number object.
 MAX VALUE – Returns maximum numerical value possible in JavaScript.
 MIN VALUE – Returns minimum numerical value possible in JavaScript.
 NEGATIVE INFINITY – Represent the value of negative infinity.
 POSITIVE INFINITY – Represent the value of infinity.
 Prototype – Add properties and methods to an object.
 Methods of Number object
 toExponential() – Converts a number into exponential notation.
 toFixed() – Formats a number with a specific number of digits to the right of the decimal.
 toLocaleString() – Returns a string value version of the current number in a format that may vary according to a browser’s locale settings.
 toPrecision() – Defines how many total digits to display of a number.
 toString() – Returns the string representation of the number’s value.
 valueOf() – Returns the number’s value.
String Object
 in JavaScript, all strings are represented as instances of the String object.
 The String object is wrapper class and member of global objects.
 String object used to perform operations on the stored text, such as finding the length of the string, searching for occurrence of certain characters within string, extracting a substring etc.
 A String is created by using literals. A string literal is either enclosed within single quotes(‘ ‘) or double quotes(“ “)
var string1= “ Ques10“ ;
 Properties of String object
 Length – Returns the length of string.
 Constructor – Returns the function that created the String object
 Prototype – Add properties and methods to an object
 Methods of String object
 charAt() – Returns the character at a specified position.
 concat() – Combines two or more strings.
 toLowerString() – Converts a string to lowercase.
 toUpperString() – Converts a string to uppercase.
 indexOf(searchtext, index) – Searches for the specified string from the beginning of the string.
 lastIndexof(searchtext, index) – Searches for the specified string from the end of the string
RegExp Object
 RegExp object used to validate the pattern of characters.
 RegExp define methods that use regular expressions to perform powerful patternmatching and search and replace functions on text.
 Regular expressions can be defined by using following ways
Using RegExp() Constructor: var RegularExpression = new RegExp(“pattern”,”flag”);
Using Literal: var RegularExpression = /pattern/flag;
 Pattern – A String that specifies the pattern of the regular expression or another regular expression.
 Flag – An optional string containing any of the “g”, “I” and “m” attributes that specify global, caseinsensitive and multiple matches respectively.
 Properties of RegExp object
 Constructor – Returns the function that created the RegExp object
 Global – Checks whether the “g” modifier is set
 ignoreCase – Checks whether the “i” modifier is set
 lastIndex – Specifies the index at which to start the next match
 multiline – Checks whether the “m” modifier is set
 source – Returns the text of the RegExp pattern
 Methods of RegExp object
 exec() – Tests for a match in a string. Returns the first match.
 test() – Tests for a match in a string. Returns true or false.
 toString() – Returns the string value of the regular expression.
 toSource() – Returns an object literal representing the specified object.