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Creates a wrapper object to allow you to work with numerical values.
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.
Number object to assign values to numeric variablesThe following example uses the Number object's properties to assign values to
several numeric variables:
biggestNum = Number.MAX_VALUE;
smallestNum = Number.MIN_VALUE;
infiniteNum = Number.POSITIVE_INFINITY;
negInfiniteNum = Number.NEGATIVE_INFINITY;
notANum = Number.NaN;
Number to convert a Date objectThe 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".
The following example converts the Date object to a numerical value using
Number as a function:
Special value representing negative infinity; returned on overflow.
The value of Number.NEGATIVE_INFINITY is the same as the negative value of the global object's
Infinity property.
This value behaves slightly differently than mathematical infinity:
Several JavaScript methods (such as the Number constructor, parseFloat, and parseInt) return
NaN if the value specified in the parameter is significantly lower than Number.MIN_VALUE.
You might use the Number.NEGATIVE_INFINITY property to indicate an error condition that returns a
finite number in case of success. Note, however, that isFinite would be more appropriate in such
a case.
In the following example, the variable smallNumber is assigned a value that is smaller than the
minimum value. When the if statement executes, smallNumber has the value "-Infinity", so
smallNumber is set to a more manageable value before continuing.
var smallNumber = (-Number.MAX_VALUE) * 2
if (smallNumber == Number.NEGATIVE_INFINITY) {
smallNumber = returnFinite();
}
Special value representing infinity; returned on overflow.
The value of Number.POSITIVE_INFINITY is the same as the value of the global object's Infinity
property.
This value behaves slightly differently than mathematical infinity:
Several JavaScript methods (such as the Number constructor, parseFloat, and parseInt) return
NaN if the value specified in the parameter is significantly higher than Number.MAX_VALUE.
You might use the Number.POSITIVE_INFINITY property to indicate an error condition that returns a
finite number in case of success. Note, however, that isFinite would be more appropriate in such
a case.
In the following example, the variable bigNumber is assigned a value that is larger than the
maximum value. When the if statement executes, bigNumber has the value "Infinity", so bigNumber
is set to a more manageable value before continuing.
var bigNumber = Number.MAX_VALUE * 2
if (bigNumber == Number.POSITIVE_INFINITY) {
bigNumber = returnFinite();
}
The largest positive representable number. The largest negative representable
number is -MAX_VALUE.
The MAX_VALUE property has a value of approximately 1.79E+308. Values larger than MAX_VALUE are
represented as "Infinity".
Because MAX_VALUE is a static property of Number, you always use it as Number.MAX_VALUE,
rather than as a property of a Number object you created.
The following code multiplies two numeric values. If the result is less than or equal to
MAX_VALUE, the func1 function is called; otherwise, the func2 function is called.
if (num1 * num2 <= Number.MAX_VALUE)
func1();
else
func2();
The smallest positive representable number -- that is, the positive number
closest to zero (without actually being zero). The smallest negative
representable number is -MIN_VALUE.
The MIN_VALUE property is the number closest to 0, not the most negative number, that JavaScript
can represent.
MIN_VALUE has a value of approximately 5e-324. Values smaller than MIN_VALUE ("underflow
values") are converted to 0.
Because MIN_VALUE is a static property of Number, you always use it as Number.MIN_VALUE,
rather than as a property of a Number object you created.
The following code divides two numeric values. If the result is greater than or equal to
MIN_VALUE, the func1 function is called; otherwise, the func2 function is called.
if (num1 / num2 >= Number.MIN_VALUE)
func1()
else
func2()
Returns a string representing the number in exponential notation.
A string representing a Number object in exponential notation with one digit before the decimal
point, rounded to fractionDigits digits after the decimal point. If the fractionDigits argument
is omitted, the number of digits after the decimal point defaults to the number of digits necessary
to represent the value uniquely.
If you use the toExponential method for a numeric literal and the numeric literal has no exponent
and no decimal point, leave a space before the dot that precedes the method call to prevent the dot
from being interpreted as a decimal point.
If a number has more digits that requested by the fractionDigits parameter, the number is rounded
to the nearest number represented by fractionDigits digits. See the discussion of rounding in the
description of the toFixed method, which also applies to toExponential.
var num=77.1234;
alert("num.toExponential() is " + num.toExponential()); //displays 7.71234e+1
alert("num.toExponential(4) is " + num.toExponential(4)); //displays 7.7123e+1
alert("num.toExponential(2) is " + num.toExponential(2)); //displays 7.71e+1
alert("77.1234.toExponential() is " + 77.1234.toExponential()); //displays 7.71234e+1
alert("77 .toExponential() is " + 77 .toExponential()); //displays 7.7e+1
An integer specifying the number of digits after the decimal point. Defaults to as many digits as necessary to specify the number.
Exponential notation of number.
Returns a string representing the number in fixed-point notation.
The number of digits to appear after the decimal point; this may be a value between 0 and 20, inclusive, and implementations may optionally support a larger range of values. If this argument is omitted, it is treated as 0.
A string representation of number that does not use
exponential notation and has exactly digits digits after the decimal place.
The number is rounded if necessary, and the fractional part is padded with
zeros if necessary so that it has the specified length. If number is greater
than 1e+21, this method simply calls Number.toString() and returns a string
in exponential notation.
Returns a human readable string representing the number using the locale of the
environment. Overrides the Object.prototype.toLocaleString method.
This method available to numbers will convert the number into a string which is suitable for presentation in the given locale.
var number = 3500
console.log(number.toLocaleString()); // Displays "3,500" in English locale
String representing the number.
Returns a string representing the number to a specified precision in fixed- point or exponential notation.
A string representing a Number object in fixed-point or
exponential notation rounded to precision significant digits. See the
discussion of rounding in the description of the toFixed method, which also
applies to toPrecision.
If the precision argument is omitted, behaves as Number.toString. If it is a non-integer value, it is rounded to the nearest integer. After rounding, if that value is not between 1 and 100 (inclusive), a RangeError is thrown.
An integer specifying the number of significant digits.
String that represents Number object.
Returns a string representing the specified object. Overrides the
Object.prototype.toString method.
The Number object overrides the toString method of the Object object; it does not inherit
Object.toString. For Number objects, the toString method returns a string representation of the
object in the specified radix.
The toString method parses its first argument, and attempts to return a string representation in
the specified radix (base). For radixes above 10, the letters of the alphabet indicate numerals
greater than 9. For example, for hexadecimal numbers (base 16), A through F are used.
If toString is given a radix not between 2 and 36, an exception is thrown.
If the radix is not specified, JavaScript assumes the preferred radix is 10.
var count = 10;
print(count.toString()); // displays "10"
print((17).toString()); // displays "17"
var x = 7;
print(x.toString(2)); // displays "111"
An integer between 2 and 36 specifying the base to use for representing numeric values.
The number represented as a string.
Returns the primitive value of the specified object. Overrides the
Object.prototype.valueOf method.
The valueOf method of Number returns the primitive value of a Number object as a number data
type.
This method is usually called internally by JavaScript and not explicitly in code.
var x = new Number();
print(x.valueOf()); // prints "0"
The primitive value of the number.