Number

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Objek Number JavaScript merupakan pembungkus object yang memungkinkan kita menggunakan nilai numerik. Objek Number dibuat menggunakan konstruktor Number().

Sintaks

new Number(value);

Parameter

value
Nilai numerik dari objek yang dibuat.

Deskripsi

Utamanya digunakan untuk objek Number antaranya:

  • Jika argument tidak dapat dikonversimenjadi angka (number), mengembalikan nilai NaN.
  • Pada konteks non-constructor (mis. tanpa new operator), Number dapat digunakan untuk melakukan konversi tipe.

Properti

Number.EPSILON
Interval terkecil dari dua angka yang disediakan.
Number.MAX_SAFE_INTEGER
Nilai maksimal integer(safe) di JavaScript (253 - 1).
Number.MAX_VALUE
Nilai positif terbesar dari nomor yang disediakan.
Number.MIN_SAFE_INTEGER
Nilai terkecil integer (safe) di 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 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.

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 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 (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.1.
ECMAScript 5.1 (ECMA-262)
The definition of 'Number' in that specification.
Standard  
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Number' in that specification.
Standard New methods and properties added: EPSILON, isFinite, isInteger, isNaN, parseFloat, parseInt
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Number' in that specification.
Draft  

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

Tag Dokumen dan Kontributor

 Kontributor untuk laman ini: rmsubekti
 Terakhir diperbarui oleh: rmsubekti,