JavaScript Native Object
JS Native Objects
JavaScript has several built-in or native objects. These objects are accessible anywhere in the program as the other objects. The following are some of the important JavaScript Native Objects:
- JavaScript number Object
- JavaScript Native Object
- JavaScript Boolean Object
- JavaScript String Object
- JavaScript Array Object
- JaaScript Date Object
- JavaScript Math Object
- JavaScript RegExp Object
JavaScript Number Object
The Number object represents numerical date, either integers or floating-point numbers. The browser automatically converts number literals to instances of the number class.
Syntax for creating a number object:
var val = new Number(number);
If the argument cannot be converted into a number, it returns NaN(Not-a-Number).
Number Properties
Property | Description |
---|---|
MAX_VALUE | Returns the maximum number value supported in JavaScript and largest number possible is (1.7976931348623157E+308) |
MIN_VALUE | Returns the smallest number value supported in JavaScript and smallest number possible is (5E-324) |
NEGATIVE_INFINITY | Returns negative infinity (-Infinity) |
NaN | Represents a value that is not a number. |
POSITIVE_INFINITY | Represents positive infinity (Infinity). |
Number Methods:
Method | Description |
---|---|
toExponential(fractionDigits) | Returns exponential value as a string. Example: var num = 100; Num.toExponential(2); // returns '1.00e+2' |
toFixed(fractionDigits) | Returns string of decimal value of a number based on specified fractionDigits.
Example: var num = 100; Num.toFixed(2); // returns '100.00' |
toLocaleString() | Returns a number as a string value according to a browser's locale settings. Example: var num = 100; Num.toLocaleString(); // returns '100' |
toPrecision(precisionNumber) | Returns number as a string with specified total digits. Example: var num = 100; Num.toPrecision(4); // returns '100.0' |
toString() | Returns the string representation of the number value. Example: var num = 100; Num.toString(); // returns '100' |
valueOf() | Returns the value of Number object. Example: var num = new Number(100); Num.valueOf(); // returns '100' |
JavaScript Boolean Object
Boolean Object is a primitive data type in JavaScript. Boolean can have only two values, true or false.
Boolean Method:
Method | Description |
---|---|
toLocaleString() | Returns string of boolean value in local browser environment. Example: var result = (1 > 2); result.toLocaleString(); // returns "false" |
toString() | Returns a string of Boolean.
Example: var result = (1 > 2); result.toString(); // returns "false" |
valueOf() | Returns the value of the Boolean object.
Example: var result = (1 > 2); result.valueOf(); // returns false |
JavaScript String object:
the String object has a number of methods.
Syntax for creating a String object
var val = new String(string);
String Properties
String Methods:
Method | Description |
---|---|
charAt(position) | Returns the character at the specified position (in Number). |
charCodeAt(position) | Returns a number indicating the Unicode value of the character at the given position (in Number). |
concat([string,,]) | Joins specified string literal values (specify multiple strings separated by comma) and returns a new string. |
indexOf(SearchString, Position) | Returns the index of first occurrence of specified String starting from specified number index. Returns -1 if not found. |
lastIndexOf(SearchString, Position) | Returns the last occurrence index of specified SearchString, starting from specified position. Returns -1 if not found. |
localeCompare(string,position) | Compares two strings in the current locale. |
match(RegExp) | Search a string for a match using specified regular expression. Returns a matching array. |
replace(searchValue, replaceValue) | Search specified string value and replace with specified replace Value string and return new string. Regular expression can also be used as searchValue. |
search(RegExp) | Search for a match based on specified regular expression. |
slice(startNumber, endNumber) | Extracts a section of a string based on specified starting and ending index and returns a new string. |
split(separatorString, limitNumber) | Splits a String into an array of strings by separating the string into substrings based on specified separator. Regular expression can also be used as separator. |
substr(start, length) | Returns the characters in a string from specified starting position through the specified number of characters (length). |
substring(start, end) | Returns the characters in a string between start and end indexes. |
toLocaleLowerCase() | Converts a string to lower case according to current locale. |
toLocaleUpperCase() | Converts a sting to upper case according to current locale. |
toLowerCase() | Returns lower case string value. |
toString() | Returns the value of String object. |
toUpperCase() | Returns upper case string value. |
valueOf() | Returns the primitive value of the specified string object. |
String HTML wrappers
Here is a list of methods which returns the string wrapped inside the appropriate HTML tag
Method | Description |
---|---|
anchor() | Creaters an HTML anchor that is used as a hypertext target. |
big() | Creates a string to be displayed in a big font as if it were in <big> tag. |
blink() | Creates a string to blink as if it were in a <blink> tag. |
bold() | Creates a string to be displayed as bold as if it were in a <b> tag. |
fixed() | Causes a string to e displayed in fixed-pitch font as if it were in a <tt> tag. |
fontcolor() | Causes a string to be displayed in the specified color as if it were in a <font color="color"> tag. |
fontsize() | Causes a string to be displayed in the specified font size a if it were in a <font size="size"> tag. |
italics() | Causes a string to be italic, as if it were in an <i> tag. |
link() | Creates an HTML hypertext link that requests another URL. |
small() | Causes a string to be displayed in a small font, as if it were in a <small>tag. |
strike() | Causes a string to e displayed as struck-out text, as if it were in a <strike> tag. |
sub() | Causes a string to be displayed as a suscript, as itf it were <sub>tag. |
sup() | Causes a string to be displayed as a superscript, as if it were in a <sup>tag. |
JavaScript Array object
The Array object is used store multiple values in a single variable.
Example:
var fruits = new Array("apple","orange","mango");
The Array parameter is a list of strings or integers. The maximum length allowed for an array is 4,294,967,295.
Array Properties
- Inext - The property represents the zero-based index of the match in the string.
- Index - This property is only present in arrays created by regular expression matches.
- Length - Reflects the number of elements in an array.
- Prototype - The prototype property allows you to add properties and methods to an object.
Array Methods
Method | Description |
---|---|
concat() | Returns new array by combining values of an array that is specified as parameter with existing array values. |
every() | Returns true or false if every element in the specified array satisfies a condition specified in the callback function. Returns false even if single element does not satisfy the condition. |
filter() | Returns a new array with all the elements that satisfy a condition specified in the callback function. |
forEach() | Executes a callback function for each elements of an array. |
indexOf() | Returns the index of the first occurrence of the specified element in the array, or -1 if it is not found. |
join() | Returns string of all the elements separated by the specified separator |
lastIndexOf() | Returns the index of the last occurrence of the specified element in the array, or -1 if it is not found. |
map() | Creates a new array with the results of calling a provided function on every element in this array. |
pop() | Removes the last element from an array and returns that element. |
push() | Adds one or more elements at the end of an array and returns the new length of the array. |
reduce() | Pass two elements simultaneously in the callback function (till it reaches the last element) and returns a single value. |
reduceRight() | Pass two elements simultaneously in the callback function from right-to-left (till it reaches the last element) and returns a single value. |
reverse() | Reverses the elements of an array. Element at last index will be first and element at 0 index will be last. |
shift() | Removes the first element from an array and returns that element. |
slice() | Returns a new array with specified start to end elements. |
some() | Returns true if at least one element in this array satisfies the condition in the callback function. |
sort() | Sorts the elements of an array. |
splice() | Adds and/or removes elements from an array. |
toString() | Returns a string representing the array and its elements. |
unshift() | Adds one or more elements to the front of an array and returns the new length of the array. |
JavaScript Date Object
The Date object is a data type built into the JavaScript language. Once a Date object is created, a number of methods are available to operate on it.
Syntax:
- new Date() - This constructor creates a Date object set to the current date and time.
- new Date(milliseconds) - When one numeric argument is passed, it is taken as the internal numeric representation of the date in milliseconds, as returned by the getTime() method.
- new Date(datestring) - When one string argument is passed, it is a string representation of a date, in the format accepted by the Date.parse() method.
- new Date(year,month,date[,hour,minut,second,millisecond])-The parameters on square brackets are optional.
Date Properties:
Method | Description |
---|---|
getDate() | Returns the day of the month (from 1-31) |
getDay() | Returns the day of the week (from 0-6) |
getFullYear() | Returns the year |
getHours() | Returns the hour (from 0-23) |
getMilliseconds() | Returns the milliseconds (from 0-999) |
getMinutes() | Returns the minutes (from 0-59) |
getMonth() | Returns the month (from 0-11) |
getSeconds() | Returns the seconds (from 0-59) |
getTime() | Returns the number of milliseconds since midnight Jan 1 1970, and a specified date |
getTimezoneOffset() | Returns the time difference between UTC time and local time, in minutes |
getUTCDate() | Returns the day of the month, according to universal time (from 1-31) |
getUTCDay() | Returns the day of the week, according to universal time (from 0-6) |
getUTCFullYear() | Returns the year, according to universal time |
getUTCHours() | Returns the hour, according to universal time (from 0-23) |
getUTCMilliseconds() | Returns the milliseconds, according to universal time (from 0-999) |
getUTCMinutes() | Returns the minutes, according to universal time (from 0-59) |
getUTCMonth() | Returns the month, according to universal time (from 0-11) |
getUTCSeconds() | Returns the seconds, according to universal time (from 0-59) |
getYear() | Deprecated. Use the getFullYear() method instead |
now() | Returns the number of milliseconds since midnight Jan 1, 1970 |
parse() | Parses a date string and returns the number of milliseconds |
setDate() | Sets the day of the month of a date object |
setFullYear() | Sets the year of a date object |
setHours() | Sets the hour of a date object |
setMilliseconds() | Sets the milliseconds of a date object |
setMinutes() | Set the minutes of a date object |
setMonth() | Sets the month of a date object |
setSeconds() | Sets the seconds of a date object |
setTime() | Sets a date to a specified number of milliseconds after/before January 1, 1970 |
setUTCDate() | Sets the day of the month of a date object, according to universal time |
setUTCFullYear() | Sets the year of a date object, according to universal time |
setUTCHours() | Sets the hour of a date object, according to universal time |
setUTCMilliseconds() | Sets the milliseconds of a date object, according to universal time |
setUTCMinutes() | Set the minutes of a date object, according to universal time |
setUTCMonth() | Sets the month of a date object, according to universal time |
setUTCSeconds() | Set the seconds of a date object, according to universal time |
setYear() | Deprecated. Use the setFullYear() method instead |
toDateString() | Converts the date portion of a Date object into a readable string |
toGMTString() | Deprecated. Use the toUTCString() method instead |
toISOString() | Returns the date as a string, using the ISO standard |
toJSON() | Returns the date as a string, formatted as a JSON date |
toLocaleDateString() | Returns the date portion of a Date object as a string, using locale conventions |
toLocaleTimeString() | Returns the time portion of a Date object as a string, using locale conventions |
toLocaleString() | Converts a Date object to a string, using locale conventions |
toString() | Converts a Date object to a string |
toTimeString() | Converts the time portion of a Date object to a string |
toUTCString() | Converts a Date object to a string, according to universal time |
UTC() | Returns the number of milliseconds in a date since midnight of January 1, 1970, according to UTC time |
valueOf() | Returns the primitive value of a Date object |
JavaScript Math Object
The math object provides the properties and methods for mathematical constants and functions.
Unlike the other global objects, Math is not a constructor.
All properties and methods of Math are static and can be called by using Math as an objcet without creating it.
Example:
var pi_val = Math.PI;//Math object need not be created var sine_val = Math.sin(30);
Math Properties
Property | Description |
---|---|
E | Returns Euler's number, the base of natural logarithms, e, approximately 2.718 |
LN2 | Returns the natural logarithm of 2, approximately 0.693 |
LN10 | Returns the natural logarithm of 10, approximately 2.302 |
LOG2E | Returns the base 2 logarithm of e, approximately 1.442 |
LOG10E | Returns the base 10 logarithm of e, approximately 0.434 |
PI | Returns the ratio of the circumference of a circle to its diameter (i.e. π). The approximate value of PI is 3.14159 |
SQRT1_2 | Returns the square root of 1/2, approximately 0.707 |
SQRT2 | Returns the square root of 2, approximately 1.414 |
JavaScript Math Methods
Method | Description |
---|---|
abs() | Returns the absolute value of a number. |
acos() | Returns the arccosine of a number, in radians. |
acosh() | Returns the hyperbolic arccosine of a number. |
asin() | Returns the arcsine of a number, in radians |
asinh() | Returns the hyperbolic arcsine of a number. |
atan() | Returns the arctangent of a number, in radians. |
atan2(y, x) | Returns the arctangent of the quotient of its arguments. |
atanh() | Returns the hyperbolic arctangent of a number. |
cbrt() | Returns the cube root of a number. |
ceil() | Returns the next integer greater than or equal to a given number (rounding up). |
cos() | Returns the cosine of the specified angle. The angle must be specified in radians. |
cosh() | Returns the hyperbolic cosine of a number. |
exp(x) | Returns ex, where x is the argument, and e is Euler's number (also known as Napier's constant), the base of the natural logarithms. |
floor() | Returns the next integer less than or equal to a given number (rounding down). |
log() | Returns the natural logarithm (base e) of a number. |
max(x, y, ...) | Returns the highest-valued number in a list of numbers. |
min(x, y, ...) | Returns the lowest-valued number in a list of numbers. |
pow(x, y) | Returns the base to the exponent power, that is, xy. |
random() | Returns a random number between 0 and 1 (including 0, but not 1). |
round() | Returns the value of a number rounded to the nearest integer. |
sin() | Returns the sign of a number (given in radians). |
sinh() | Returns the hyperbolic sine of a number. |
sqrt() | Returns the square root of a number. |
tan() | Returns the tangent of a number. |
tanh() | Returns the hyperbolic tangent of a number. |
trunc(x) | Returns the integer part of a number by removing any fractional digits. |
Regular expressions and regular objects
A regular expression is an object that describes a pattern of characters.
The JavaScript RegExp class represents regular expressions, And both String and RegExp define methods that use regular expressions to perform powerful pattern-matching and search-and-replace functions on text.
Syntax:
var pattern = new RegExp(pattern, attributes); var pattern = /pattern/attributes;
Bracketts:
Brackets ([]) have a special meaning when used in the context of regualr expression.
they are used to find a range of characters.
- [...] - Any one character between the brackets.
- [^...] - Any one character not between the brackets.
- [0-9] - It matches any decimal digit from 0 through 9.
- [a-z] - it matches any character from lowercase a through lowercase z.
- [A-Z] - it matches any character from uppercase A through uppercase Z.
- [a-Z] - It matches any character from lowercase a through uppercase Z.
Quantifiers:
The frequency or position of bracketed character sequences and single characters can be denoted by a special character.
Each special character have a specific connotation. The +,*,?, and $ flags all follow a character sequence.
- p+ -It matches any string containing at least one p.
- p* -It matches nay string containing zero or more p's.
- p? -It matches any string containing one or more p's.
- p{N} -It matches any string containing a sequence of N p's.
- p{2,3} -It matches any string containing a sequence of two or three p's.
- p{2,} -It matches any string containing a sequence of at least two p's.
- p$ -It matches any string with p at the end of it.
- ^p -It matches any string with p at the beginning of it.
RefExp Properties
Property | Description |
---|---|
Global | Specifies if the "g" modifier is set |
ingnoreCase | Specifies if the "i" modifies is set. |
LastIndex | The index at which to start the next match. |
Multiline | Specifies if the "m" modifier is set. |
Source | The text of the pattern. |
Global | Specifies if the "g" modifier is set. |
RefExp Methods
Property | Description |
---|---|
exec() | Executes a search for a match in its string parameter. |
test() | Tests for a match in its string parameter. |
toSource() | Returns an object literal representing the specified object; you can use this value to create a new object. |
toString() | Returns a string representing the specified object. |