### JavaScript Number Methods

January 26, 2020

JavaScript Number Methods

With JavaScript, methods and properties are also available to primitive values, because JavaScript treats primitive values as objects when executing methods and properties. Number methods help you work with numbers.

### The toString() Method

The toString() method returns a number as a string. All number methods can be used on any type of numbers (literals, variables, or expressions):

``````var x = 123;
x.toString();            // returns 123 from variable x
(123).toString();        // returns 123 from literal 123
(100 + 23).toString();   // returns 123 from expression 100 + 23

var myNumber = 32;
myNumber.toString(10);  // returns 32
myNumber.toString(32);  // returns 10
myNumber.toString(16);  // returns 20
myNumber.toString(8);   // returns 40
myNumber.toString(2);   // returns 100000``````

### The toFixed() Method

toFixed() returns a string, with the number written with a specified number of decimals:

``````var x = 9.656;
x.toFixed(0);           // returns 10
x.toFixed(2);           // returns 9.66
x.toFixed(4);           // returns 9.6560
x.toFixed(6);           // returns 9.656000``````

### The toPrecision() Method

toPrecision() returns a string, with a number written with a specified length:

``````var x = 9.656;
x.toPrecision();        // returns 9.656
x.toPrecision(2);       // returns 9.7
x.toPrecision(4);       // returns 9.656
x.toPrecision(6);       // returns 9.65600``````

### Converting Variables to Numbers

There are 3 JavaScript methods that can be used to convert variables to numbers:

• The Number() method
• The parseInt() method
• The parseFloat() method

These methods are not number methods, but global JavaScript methods.

``````Number(true);          // returns 1
Number(false);         // returns 0
Number("10");          // returns 10
Number("  10");        // returns 10
Number("10  ");        // returns 10
Number(" 10  ");       // returns 10
Number("10.33");       // returns 10.33
Number("10,33");       // returns NaN
Number("10 33");       // returns NaN
Number("John");        // returns NaN

Number(new Date("2017-09-30"));    // returns 1506729600000``````
``````parseInt("10");         // returns 10
parseInt("10.33");      // returns 10
parseInt("10 20 30");   // returns 10
parseInt("10 years");   // returns 10
parseInt("years 10");   // returns NaN ``````
``````parseFloat("10");        // returns 10
parseFloat("10.33");     // returns 10.33
parseFloat("10 20 30");  // returns 10
parseFloat("10 years");  // returns 10
parseFloat("years 10");  // returns NaN``````

### Number Properties

PropertyDescription
MAX_VALUEReturns the largest number possible in JavaScript
MIN_VALUEReturns the smallest number possible in JavaScript
POSITIVE_INFINITYRepresents infinity (returned on overflow)
NEGATIVE_INFINITYRepresents negative infinity (returned on overflow)
NaNRepresents a "Not-a-Number" value