+ Addition
– Subtraction
* Multiplication
/ Division float division
% Modulus works for floating point

JavaScript types

The data type of NaN is number
The data type of an array is object
The data type of a date is object
The data type of null is object
The data type of an undefined variable is undefined *
The data type of a variable that has not been assigned a value is also undefined *
JavaScript Type Conversion
typeof use
console.log(typeof c);

The constructor Property
The constructor property returns the constructor function for all JavaScript variables.

Convert to String


String(x) // returns a string from a number variable x
String(123) // returns a string from a number literal 123
String(100 + 23) // returns a string from a number from an expression
x.toString()
(123).toString()
(100 + 23).toString()

DatesCreating Date Objects
Date objects are created with the new Date() constructor.

There are 4 ways to create a new date object:

new Date()
new Date(year, month, day, hours, minutes, seconds, milliseconds)
new Date(milliseconds)
new Date(date string)

new Date()


Method Description
getFullYear() Get the year as a four digit number (yyyy)
getMonth() Get the month as a number (0-11)
getDate() Get the day as a number (1-31)
getHours() Get the hour (0-23)
getMinutes() Get the minute (0-59)
getSeconds() Get the second (0-59)
getMilliseconds() Get the millisecond (0-999)
getTime() Get the time (milliseconds since January 1, 1970)
getDay() Get the weekday as a number (0-6)

new Date() creates a new date object with the current date and time:
var d = new Date("October 13, 2014 11:13:00");

JavaScript Date Input
There are generally 3 types of JavaScript date input formats:

Type Example
ISO Date "2015-03-25" (The International Standard)
Short Date "03/25/2015"
Long Date "Mar 25 2015" or "25 Mar 2015"





setDate() Set the day as a number (1-31)
setFullYear() Set the year (optionally month and day)
setHours() Set the hour (0-23)
setMilliseconds() Set the milliseconds (0-999)
setMinutes() Set the minutes (0-59)
setMonth() Set the month (0-11)
setSeconds() Set the seconds (0-59)
setTime() Set the time (milliseconds since January 1, 1970)