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Number

The Number JavaScript object is a wrapper object allowing you to work with numerical values. A Number object is created using the Number() constructor.

Syntax

new Number(value);

Parameters

value
The numeric value of the object being created.

Description

The primary uses of the Number object are:

  • If the argument cannot be converted into a number, it returns NaN.
  • In a non-constructor context (i.e., without the new operator), Number can be used to perform a type conversion.

Properties

Number.EPSILON
The smallest interval between two representable numbers.
Number.MAX_SAFE_INTEGER
The maximum safe integer in JavaScript (253 - 1).
Number.MAX_VALUE
The largest positive representable number.
Number.MIN_SAFE_INTEGER
The minimum safe integer in JavaScript (-(253 - 1)).
Number.MIN_VALUE
The smallest positive representable number - that is, the positive number closest to zero (without actually being zero).
Number.NaN
Special "not a number" value.
Number.NEGATIVE_INFINITY
Special value representing negative infinity; returned on overflow.
Number.POSITIVE_INFINITY
Special value representing infinity; returned on overflow.
Number.prototype
Allows the addition of properties to a Number object.

Methods

Number.isNaN()
Determine whether the passed value is NaN.
Number.isFinite()
Determine whether the passed value is a finite number.
Number.isInteger()
Determine whether the passed value is an integer.
Number.isSafeInteger()
Determine whether the passed value is a safe integer (number between -(253 - 1) and 253 - 1).
Number.toInteger()
Used to evaluate the passed value and convert it to an integer (or Infinity), but has been removed.
Number.parseFloat()
The value is the same as parseFloat() of the global object.
Number.parseInt()
The value is the same as parseInt() of the global object.

Number instances

All Number instances inherit from Number.prototype. The prototype object of the Number constructor can be modified to affect all Number instances.

Methods

Number.prototype.toExponential()
Returns a string representing the number in exponential notation.
Number.prototype.toFixed()
Returns a string representing the number in fixed-point notation.
Number.prototype.toLocaleString()
Returns a string with a language sensitive representation of this number. Overrides the Object.prototype.toLocaleString() method.
Number.prototype.toPrecision()
Returns a string representing the number to a specified precision in fixed-point or exponential notation.
Number.prototype.toSource()
Returns an object literal representing the specified Number object; you can use this value to create a new object. Overrides the Object.prototype.toSource() method.
Number.prototype.toString()
Returns a string representing the specified object in the specified radix (base). Overrides the Object.prototype.toString() method.
Number.prototype.valueOf()
Returns the primitive value of the specified object. Overrides the Object.prototype.valueOf() method.

Examples

Using the Number object to assign values to numeric variables

The following example uses the Number object's properties to assign values to several numeric variables:

var biggestNum = Number.MAX_VALUE;
var smallestNum = Number.MIN_VALUE;
var infiniteNum = Number.POSITIVE_INFINITY;
var negInfiniteNum = Number.NEGATIVE_INFINITY;
var notANum = Number.NaN;

Integer range for Number

The following example shows the minimum and maximum integer values that can be represented as Number object (for details, refer to ECMAScript standard, chapter 6.1.6 The Number Type):

var biggestInt = 9007199254740991;
var smallestInt = -9007199254740991;

When parsing data that has been serialized to JSON, integer values falling out of this range can be expected to become corrupted when JSON parser coerces them to Number type. Using String instead is a possible workaround.

Using Number to convert a Date object

The following example converts the Date object to a numerical value using Number as a function:

var d = new Date('December 17, 1995 03:24:00');
console.log(Number(d));

This logs "819199440000".

Convert numeric strings and null to numbers

Number('123')     // 123
Number('12.3')    // 12.3
Number('123e-1')  // 12.3
Number('')        // 0
Number(null)      // 0 
Number('0x11')    // 17
Number('0b11')    // 3
Number('0o11')    // 9
Number('foo')     // NaN
Number('100a')    // NaN

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
Basic support Yes Yes 1 Yes Yes Yes
EPSILON Yes Yes 25 No Yes 9
MAX_SAFE_INTEGER 34 Yes 31 No Yes 9
MAX_VALUE Yes Yes 1 Yes Yes Yes
MIN_SAFE_INTEGER 34 Yes 31 No Yes 9
MIN_VALUE Yes Yes 1 Yes Yes Yes
NEGATIVE_INFINITY Yes Yes 1 Yes Yes Yes
NaN Yes Yes 1 Yes Yes Yes
POSITIVE_INFINITY Yes Yes 1 Yes Yes Yes
isFinite 19 Yes 16 No 15 9
isInteger Yes Yes 16 No Yes Yes
isNaN 25 Yes 15 No Yes 9
isSafeInteger Yes Yes 32 No Yes 10
parseFloat Yes Yes 25 No Yes 9
parseInt Yes Yes 25 No Yes 9
prototype Yes Yes 1 Yes Yes Yes
toExponential Yes Yes 1 Yes Yes Yes
toFixed Yes Yes 1 Yes Yes Yes
toInteger No No 16 — 32 No No No
toLocaleString Yes Yes 1 Yes Yes Yes
toPrecision Yes Yes 1 Yes Yes Yes
toSource No No 1 No No No
toString Yes Yes 1 Yes Yes Yes
valueOf Yes Yes 1 Yes Yes Yes
Mobile
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support Yes Yes Yes 4 Yes Yes Yes
EPSILON Yes Yes Yes 25 Yes 9 Yes
MAX_SAFE_INTEGER Yes Yes Yes 31 Yes 9 Yes
MAX_VALUE Yes Yes Yes 4 Yes Yes Yes
MIN_SAFE_INTEGER Yes Yes Yes 31 Yes 9 Yes
MIN_VALUE Yes Yes Yes 4 Yes Yes Yes
NEGATIVE_INFINITY Yes Yes Yes 4 Yes Yes Yes
NaN Yes Yes Yes 4 Yes Yes Yes
POSITIVE_INFINITY Yes Yes Yes 4 Yes Yes Yes
isFinite Yes Yes Yes 16 Yes Yes Yes
isInteger Yes Yes Yes 16 Yes Yes Yes
isNaN Yes Yes Yes 15 Yes 9 Yes
isSafeInteger Yes Yes Yes 32 Yes Yes Yes
parseFloat Yes Yes Yes 25 Yes 9 Yes
parseInt Yes Yes Yes 25 Yes 9 Yes
prototype Yes Yes Yes 4 Yes Yes Yes
toExponential Yes Yes Yes 4 Yes Yes Yes
toFixed Yes Yes Yes 4 Yes Yes Yes
toInteger No No No 16 — 32 No No No
toLocaleString Yes Yes Yes 4 Yes Yes Yes
toPrecision Yes Yes Yes 4 Yes Yes Yes
toSource No No No 4 No No No
toString Yes Yes Yes 4 Yes Yes Yes
valueOf Yes Yes Yes 4 Yes Yes Yes
Server
Node.js
Basic support Yes
EPSILON 0.12
MAX_SAFE_INTEGER 0.12
MAX_VALUE Yes
MIN_SAFE_INTEGER 0.12
MIN_VALUE Yes
NEGATIVE_INFINITY Yes
NaN Yes
POSITIVE_INFINITY Yes
isFinite 0.10
isInteger 0.12
isNaN 0.10
isSafeInteger 0.12
parseFloat 0.12
parseInt 0.12
prototype Yes
toExponential Yes
toFixed Yes
toInteger No
toLocaleString Yes
toPrecision Yes
toSource No
toString Yes
valueOf Yes

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number