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    Number

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    Summary

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

    Constructor

    new Number(value);

    Parameters

    value
    The numeric value of the object being created.

    Description

    The primary uses for 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.
    Properties inherited from Function:

    Methods

    For methods available on Number instances, see Methods of Number instances.
    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.
    Methods inherited from Function:

    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

    Example: 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;
    

    Example: Integer range for Number

    The following example shows minimum and maximum integer values that can be represented as Number object (for details, refer to EcmaScript standard, chapter 8.5 The Number Type):

    var biggestInt = 9007199254740992;
    var smallestInt = -9007199254740992;
    

    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.

    Example: 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');
    print(Number(d));
    

    This displays "819199440000".

    Example: Convert numeric strings to numbers

    Number("123")     // 123
    Number("")        // 0
    Number("0x11")    // 17
    Number("0b11")    // 3
    Number("0o11")    // 9
    Number("foo")     // NaN
    Number("100a")    // NaN
    

    Specifications

    Specification Status Comment
    ECMAScript 1st Edition. Standard Initial definition. Implemented in JavaScript 1.1.
    ECMAScript 5.1 (ECMA-262)
    The definition of 'Number' in that specification.
    Standard  
    ECMAScript 6 (ECMA-262)
    The definition of 'Number' in that specification.
    Release Candidate New methods and properties added: (EPSILON, isFinite, isInteger, isNaN, parseFloat, parseInt)

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

    See also