Array of Object
The Array object is used to store multiple values in a
single variable.
Array Object
Properties
Property Description
Constructor Returns
the function that created the Array object's prototype
Length Sets
or returns the number of elements in an array
prototype Allows
you to add properties and methods to an Array object
Array Object Methods
Method Description
concat() Joins
two or more arrays, and returns a copy of the joined arrays
indexOf() Search
the array for an element and returns its position
join() Joins
all elements of an array into a string
lastIndexOf() Search
the array for an element, starting at the end, and returns its position
pop() Removes
the last element of an array, and returns that element
push() Adds
new elements to the end of an array, and returns the new length
reverse() Reverses
the order of the elements in an array
shift() Removes
the first element of an array, and returns that element
slice() Selects
a part of an array, and returns the new array
sort() Sorts
the elements of an array
splice() Adds/Removes
elements from an array
Boolean Object
The Boolean object is used to convert a non-Boolean value to
a Boolean value (true or false).
For a tutorial about the Boolean object, read our JavaScript
Boolean Object tutorial.
Boolean Object
Properties
Property Description
constructor Returns
the function that created the Boolean object's prototype
prototype Allows
you to add properties and methods to a Boolean object
Boolean Object
Methods
Method Description
toString() Converts
a Boolean value to a string, and returns the result
valueOf() Returns
the primitive value of a Boolean object
Date Object
The Date object is used to work with dates and times.
Date objects are created with new Date().
There are four ways of instantiating a date:
var d = new Date();
var d = new Date(milliseconds);
var d = new Date(dateString);
var d = new Date(year, month, day, hours, minutes, seconds,
milliseconds);
For a tutorial about date and times, read our JavaScript
Date Object tutorial.
Date Object
Properties
Property Description
constructor Returns
the function that created the Date object's prototype
prototype Allows
you to add properties and methods to an object
Date Object Methods
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 (four digits)
getHours() Returns
the hour (from 0-23)
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
getUTCDate() Returns
the day of the month, according to universal time (from 1-31)
toDateString() Converts
the date portion of a Date object into a readable string
toTimeString() Converts
the time portion of a Date object to a string
valueOf() Returns
the primitive value of a Date object
Math Object
Math is not a constructor. All properties/methods of Math
can be called by using Math as an object, without creating it.
Syntax
var x = Math.PI; // Returns PI
var y = Math.sqrt(16); // Returns the square root of 16
Math Object
Properties
Property Description
E Returns
Euler's number (approx. 2.718)
LN2 Returns the
natural logarithm of 2 (approx. 0.693)
LN10 Returns the
natural logarithm of 10 (approx. 2.302)
LOG2E Returns the
base-2 logarithm of E (approx. 1.442)
Math Object Methods
Method Description
abs(x) Returns
the absolute value of x
asin(x) Returns
the arcsine of x, in radians
ceil(x) Returns
x, rounded upwards to the nearest integer
log(x) Returns
the natural logarithm (base E) of x
Number Object
The Number object is an object wrapper for primitive numeric
values.
Number objects are created with new Number().
Syntax
var num = new Number(value);
Number Object Properties
Property Description
constructor Returns
the function that created the Number object's prototype
MAX_VALUE Returns
the largest number possible in JavaScript
MIN_VALUE Returns
the smallest number possible in JavaScript
prototype Allows
you to add properties and methods to an object
Number Object Methods
Method Description
toFixed(x) Formats
a number with x numbers of digits after the decimal point
toString() Converts
a Number object to a string
valueOf() Returns
the primitive value of a Number object
String Object
The String object is used to manipulate a stored piece of
text.
String objects are created with new String().
Syntax
var txt = new String("string");
or more simply:
var txt = "string";
For a tutorial about the String object, read our JavaScript
String Object tutorial.
String Object
Properties
Property Description
constructor Returns
the function that created the String object's prototype
length Returns the length of a string
prototype Allows
you to add properties and methods to an object
String Object Methods
Method Description
charAt() Returns
the character at the specified index
charCodeAt() Returns
the Unicode of the character at the specified index
concat() Joins
two or more strings, and returns a copy of the joined strings
indexOf() Returns
the position of the first found occurrence of a specified value in a string
JavaScript Global
Properties
Property Description
Infinity A numeric
value that represents positive/negative infinity
NaN "Not-a-Number"
value
undefined Indicates
that a variable has not been assigned a value
JavaScript Global
Functions
Function Description
decodeURI() Decodes
a URI
encodeURI() Encodes
a URI
escape() Encodes
a string
eval() Evaluates
a string and executes it as if it was script code
isFinite() Determines
whether a value is a finite, legal number
isNaN() Determines
whether a value is an illegal number
Number() Converts
an object's value to a number
