GeezerVison is showing www.tutorialspoint.com — JavaScript - The Number Object

Selected Reading

JavaScript - The Number Object

Quiz

The JavaScript Number object represents numerical data as floating-point numbers. It contains different properties (constants) and methods for working on numbers. In general, you do not need to worry about Number objects because the browser automatically converts number literals to instances of the number class.

A JavaScript Number object can be defined using the Number constructor. Other types of data such as strings, etc., can be converted to numbers using Number() function.

A JavaScript number is always stored as a floating-point value (decimal number). JavaScript does not make a distinction between integer values and floating-point values. JavaScript represents numbers using the 64-bit floating-point format defined by the IEEE 754 standard.

Syntax

The syntax for creating a number object is as follows −

const val = new Number(number);

In the place of number, if you provide any non-number argument, then the argument cannot be converted into a number, it returns NaN (Not-a-Number).

We can also create the number primitives by assigning the numeric values to the variables −

let num1 = 24;
let num2 = 35.65;

The JavaScript automatically converts the number primitive to the Number objects. So we can use all properties and methods of Number object on number primitives.

Number Properties

Here is a list of each property and their description.

Sr.No.	Property & Description
1	EPSILON It represents the difference between 1 and the smallest floating point number greater than 1.
2	MAX_SAFE_INTEGER It returns the maximum safe integer value.
3	MAX_VALUE The largest possible value a number in JavaScript can have 1.7976931348623157E+308.
4	MIN_SAFE_INTEGER It returns the minimum safe integer value.
5	MIN_VALUE The smallest possible value a number in JavaScript can have 5E-324.
6	NaN Equal to a value that is not a number.
7	NEGATIVE_INFINITY A value that is less than MIN_VALUE.
8	POSITIVE_INFINITY A value that is greater than MAX_VALUE
9	prototype A static property of the Number object. Use the prototype property to assign new properties and methods to the Number object in the current document.
10	constructor Returns the function that created this object's instance. By default this is the Number object.

Number Methods

The Number object contains only the default methods (instance and static methods) that are a part of every object's definition.

Instance Methods

Sr.No.	Method & Description
1	toExponential() Forces a number to display in exponential notation, even if the number is in the range of standard notation.
2	toFixed() Formats a number with a specific number of digits to the right of the decimal.
3	toLocaleString() Returns a string value version of the current number in a format that may vary according to local settings.
4	toPrecision() Defines how many total digits (including digits to the left and right of the decimal) to display of a number.
5	toString() Returns the string representation of the number's value.
6	valueOf() Returns the number's value.

Static Methods

Sr.No.	Method & Description
1	isNaN() It checks whether the value is a valid number or not.
2	isFinite() It checks whether the number is finite.
3	isInteger() Returns Boolean when the number is an integer value.
4	isSafeInteger() It ensures that the integer is a safe integer.
5	parseFloat() Parses the float value from the string.
6	parseInt() Parses the integer value from the string.

Examples

Let's take a few examples to demonstrate the properties and methods of Number.

Example: Creating Number Object

In the example below, the num variable contains the number object having the value 20. In the output, you can see that type of the num variable is an object.

<html>
<body>
   <p id = "output"> </p>
   <script>
      const num = new Number(20);
      document.getElementById("output").innerHTML =  
      "num = " + num + "<br>" + 
      "typeof num : " + typeof num;
   </script>
</body>
</html>

Output

num = 20
typeof num : object

Example: Number Properties

In the example below, we have displayed some Number properties. You should try to print more properties.

<html>
<body>
<div id="output"></div>
   <script>
      document.getElementById("output").innerHTML =
      "Max Value : " + Number.MAX_VALUE + "<br>"
      +"Min Value : " + Number.MIN_VALUE + "<br>"
      +"Positive Infinity : " + Number.POSITIVE_INFINITY + "<br>"
      +"Negative Infinity : " + Number.NEGATIVE_INFINITY + "<br>"
      +"NaN : " + Number.NaN + "<br>";
   </script>
</body>
</html>

Output

Max Value : 1.7976931348623157e+308
Min Value : 5e-324
Positive Infinity : Infinity
Negative Infinity : -Infinity
NaN : NaN

Example: Number Methods

In the example below, we have used some properties of Number. You can try edit the program to use more methods.

<html>
<body>
<div id="output"></div>
   <script>
      const num = 877.5312
      document.getElementById("output").innerHTML =
      "num.toExponetial() is : " + num.toExponential()+ "<br>"
      +"num.toFixed() is : " + num.toFixed() + "<br>"
      +"num.toPrecision(2) is : " + num.toPrecision(2) + "<br>";
   </script>
</body>
</html>

Output

num.toExponetial() is : 8.775312e+2
num.toFixed() is : 878
num.toPrecision(2) is : 8.8e+2

JavaScript Number() Function

The Number() function converts the variable into a number. You can use it to change the data type of the variable.

let num = Number(val)

Here val is a variable or value to convert into a number. It doesn't create a number object instead it returns a primitive value.

Example

We passed the integer and string value to the Number() function in the example below. In the output, the code prints the numeric values. The type of the num2 variable is a number, as the Number() function returns the primitive number value.

<html>
<body>
   <p id = "output"> </p>
   <script>
      let num = Number(10);
      document.getElementById("output").innerHTML = 
      "num = " + num + "<br>" + 
	   "typeof num = " + typeof num;
   </script>
</body>
</html>

Output

num = 10
typeof num = number

Example: Converting Numeric Strings to Numbers

We can use the Number() function to convert numeric strings to numbers. Try the following example −

<html>
<body>
   <p id = "output"> </p>
   <script>
      let str = "102.34";
      let num = Number(str);
      document.getElementById("output").innerHTML =
      "num = " + num + "<br>" +
      "typeof num = " + typeof num;
   </script>
</body>
</html>

Output

num = 102.34
typeof num = number

Try the above example with different numbers such as integers, floating point, octal, hexadecimal, etc.

Previous Quiz Next