Javascript Number Methods
Let's see the below list of JavaScript number methods with their description.
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Methods |
Description |
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It determines whether the given value is a finite number. |
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It determines whether the given value is an integer. |
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It converts the given string into a floating point number. |
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It converts the given string into an integer number. |
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It returns the string that represents exponential notation of the given number. |
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It returns the string that represents a number with exact digits after a decimal point. |
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It returns the string representing a number of specified precision. |
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It returns the given number in the form of string. |
toString() Method
The toString() method modify a number as a string.
All number methods might be used on any type of numbers (literals, variables, or expressions):
var x = 456;
x.toString(); // returns 456 from variable x
(456).toString(); // returns 456 from literal 456
(100 + 25).toString(); // returns 125 from expression 100 + 25
toExponential() Method
toExponential() returns a string, with a number that is rounded and written using exponential notation.
var x = 9.656;
x.toExponential(2); // returns 9.66e+0
x.toExponential(4); // returns 9.6560e+0
x.toExponential(6); // returns 9.656000e+0
The toFixed() Method
toFixed() returns a string, with specified number of decimals:
var x = 8.656;
x.toFixed(0); // returns 9
x.toFixed(2); // returns 8.66
x.toFixed(4); // returns 8.6560
x.toFixed(6); // returns 8.656000
Note:- toFixed(2) is perfect for working with money.
toPrecision() Method
toPrecision() returns a string, with a specified length:
var x = 8.656;
x.toPrecision(); // returns 8.656
x.toPrecision(2); // returns 8.7
x.toPrecision(4); // returns 8.656
x.toPrecision(6); // returns 8.65600
valueOf() Method
valueOf() returns a number as a number.
var x = 456;
x.valueOf(); // returns 456 from variable x
(456).valueOf(); // returns 456 from literal 456
(100 + 25).valueOf(); // returns 125 from expression 100 + 25
Note:- All JavaScript data types have a valueOf() and a toString() method.
Converting Variables to Numbers
There are 3 methods that can be used to convert or modify variables to numbers:
- The Number() method
- The parseInt() method
- The parseFloat() method
These methods are not number methods, but global JS methods.
Number() Method
Number() can be used to convert variables to numbers:
Number(true); // returns 1
Number(false); // returns 0
Number("11"); // returns 11
Number(" 11"); // returns 11
Number("11 "); // returns 11
Number(" 11 "); // returns 11
Number("11.33"); // returns 11.33
Number("11,33"); // returns NaN
Number("11 33"); // returns NaN
Number("Daniel"); // returns NaN
Note:- If the number cannot be converted, NaN (Not a Number) is returned.
Number() Method Used on Dates
Number(new Date("2020-04-28")); // returns 1588032000000
parseInt() Method
parseInt() parses a string and returns a whole number. Spaces are allowed. Only the first number will be returned:
parseInt("20"); // returns 20
parseInt("20.33"); // returns 20
parseInt("20 30 40"); // returns 20
parseInt("20 years"); // returns 20
parseInt("years 20"); // returns NaN
parseFloat() Method
parseFloat() parses a string and returns a number. Spaces are allowed. Only the first number is returned:
parseFloat("20"); // returns 20
parseFloat("20.33"); // returns 20.33
parseFloat("20 30 40"); // returns 20
parseFloat("20 years"); // returns 20
parseFloat("years 20"); // returns NaN
Number Properties Cannot be Used on Variables
Number properties belongs to the JavaScript's number object called Number.
These properties can only be accessed or used as Number.MAX_VALUE.
Using myNumber.MAX_VALUE, where myNumber is a variable, expression, or value, will return undefined:
var x = 7;
var y = x.MAX_VALUE; // y becomes undefined
