HTML tutorial
CSS3 tutorial
Bootstrap tutorial
JavaScript tutorial
JQuery tutorial
AngularJS tutorial
React tutorial
NodeJS tutorial
PHP tutorial
Python tutorial
Python3 tutorial
Django tutorial
Linux tutorial
Docker tutorial
Ruby tutorial
Java tutorial
C tutorial
C ++ tutorial
Perl tutorial
JSP tutorial
Lua tutorial
Scala tutorial
Go tutorial
ASP.NET tutorial
C # tutorial
Number methods help you work with numbers
Primitive values (like 3.14 or 2014), cannot have properties and methods (because they are not objects).
But with JavaScript, methods and properties are also available to primitive values, because JavaScript treats primitive values as objects when executing methods and properties.
The toString()
method returns a number as a string.
All number methods can be used on any type of numbers (literals, variables, or expressions):
let x = 123;
x.toString();
(123).toString();
(100 + 23).toString();
toExponential()
returns a string, with a number rounded and written using exponential notation.
A parameter defines the number of characters behind the decimal point:
let x = 9.656;
x.toExponential(2);
x.toExponential(4);
x.toExponential(6);
The parameter is optional. If you don't specify it, JavaScript will not round the number.
toFixed()
returns a string, with the number
written with a specified number of
decimals:
let x = 9.656;
x.toFixed(0);
x.toFixed(2);
x.toFixed(4);
x.toFixed(6);
toFixed(2)
is perfect for working with money.
toPrecision()
returns a string, with a number written with a
specified length:
let x = 9.656;
x.toPrecision();
x.toPrecision(2);
x.toPrecision(4);
x.toPrecision(6);
valueOf()
returns a number as a number.
let x = 123;
x.valueOf();
(123).valueOf();
(100 + 23).valueOf();
In JavaScript, a number can be a primitive value (typeof = number) or an object (typeof = object).
The valueOf()
method is used internally in JavaScript to convert Number
objects to primitive values.
There is no reason to use it in your code.
All JavaScript data types have a valueOf()
and a toString()
method.
There are 3 JavaScript methods that can be used to convert variables to numbers:
Number()
methodparseInt()
methodparseFloat()
methodThese methods are not number methods, but global JavaScript methods.
JavaScript global methods can be used on all JavaScript data types.
These are the most relevant methods, when working with numbers:
Method | Description |
---|---|
Number() | Returns a number, converted from its argument. |
parseFloat() | Parses its argument and returns a floating point number |
parseInt() | Parses its argument and returns an integer |
Number()
can be used to convert JavaScript variables to numbers:
Number(true);
Number(false);
Number("10");
Number(" 10");
Number("10 ");
Number(" 10 ");
Number("10.33");
Number("10,33");
Number("10 33");
Number("John");
If the number cannot be converted, NaN
(Not a Number) is returned.
Number()
can also convert a date to a number.
Number(new Date("1970-01-01"))
The Number()
method returns the number of milliseconds since 1.1.1970.
The number of milliseconds between 1970-01-02 and 1970-01-01 is 86400000:
Number(new Date("1970-01-02"))
Number(new Date("2017-09-30"))
parseInt()
parses a string and returns a whole number. Spaces are
allowed. Only the first number is returned:
parseInt("-10");
parseInt("-10.33");
parseInt("10");
parseInt("10.33");
parseInt("10 20 30");
parseInt("10 years");
parseInt("years 10");
If the number cannot be converted, NaN
(Not a Number) is returned.
parseFloat()
parses a string and returns a number. Spaces are
allowed. Only the first number is returned:
parseFloat("10");
parseFloat("10.33");
parseFloat("10 20 30");
parseFloat("10 years");
parseFloat("years 10");
If the number cannot be converted, NaN
(Not a Number) is returned.
Property | Description |
---|---|
MAX_VALUE | Returns the largest number possible in JavaScript |
MIN_VALUE | Returns the smallest number possible in JavaScript |
POSITIVE_INFINITY | Represents infinity (returned on overflow) |
NEGATIVE_INFINITY | Represents negative infinity (returned on overflow) |
NaN | Represents a "Not-a-Number" value |
MAX_VALUE
returns the largest possible number in JavaScript.
let x = Number.MAX_VALUE;
MIN_VALUE
returns the lowest possible number in JavaScript.
let x = Number.MIN_VALUE;
let x = Number.POSITIVE_INFINITY;
POSITIVE_INFINITY
is returned on overflow:
let x = 1 / 0;
let x = Number.NEGATIVE_INFINITY;
NEGATIVE_INFINITY
is returned on overflow:
let x = -1 / 0;
let x = Number.NaN;
NaN
is a JavaScript reserved word indicating that a number is not a legal number.
Trying to do arithmetic with a non-numeric string will result in NaN
(Not a
Number):
Number properties belongs to the JavaScript's number object wrapper called Number.
These properties can only be accessed as Number.MAX_VALUE
.
Using myNumber.MAX_VALUE, where myNumber is a variable, expression,
or value, will return undefined
:
let x = 6;
x.MAX_VALUE
For a complete Number reference, visit our:
Complete JavaScript Number Reference.
The reference contains descriptions and examples of all Number properties and methods.