JAVASCRIPT BASICS
- Introduction to JavaScript
- Javascript Features
- JavaScript in HTML
- JavaScript Syntax
- Output in JavaScript
- JavaScript Variables
- Javascript let Keyword
- JS Literals and Keywords
- JavaScript Data Types
- JavaScript Operators
- JavaScript Events
- Javascript const Keyword
JAVASCRIPT FLOW CONTROL AND LOOPS
- JS if, else and else if
- JavaScript for Loop
- JS while and do-while loop
- JS Switch case
- JS break and continue
JAVASCRIPT ADVANCED
- JavaScript Strings
- JavaScript String Methods
- JavaScript Array
- JavaScript Regular Expression
- JavaScript Popup Boxes
- JavaScript Functions
- JavaScript Default Parameters
- JavaScript Rest Parameters
- JavaScript Arrow Function
- JavaScript Errors
- JavaScript Error Handling
- JavaScript Cookies
JAVASCRIPT OBJECT
- JavaScript Objects
- JavaScript User-defined Object
- JavaScript Boolean Object
- JavaScript Number Object
- JavaScript Math Object
- JavaScript Date Object
- JavaScript RegExp Object
JAVASCRIPT WEB API AND INTERFACES
JavaScript Number is a built-in wrapper object which is used to work with numerical values. A Number object can be created using the Number()
constructor.
All numbers are 64 bit(8 bytes) floating-point numbers. Unlike C or C++, there are no data types like integer, float, etc, to define numbers in JavaScript(recently with ECMAScript2016, JavaScript has started supporting BigInt
type for integers).
Creating JavaScript Number Object
If we use the Number()
constructor with the new
keyword we can create the Number object.
let num = new Number(SOME_NUMERIC_VALUE);
and if we use the Number()
function (in a non-constructor context) without the new
keyword, it will create a primitive number type, which can also be used for type conversion.
Let’s take an example,
let x = new Number(290.78);
document.write(x + "<br/>");
document.write(typeof x + "<br/>");
290.78 object
Since Number is a built-in object then it has some properties and methods to work on numerical type.
JavaScript Number Object Properties
Following are the properties for the Number object:
Property | Description |
---|---|
Number.EPSILON | The smallest interval between two representable numbers. |
Number.MAX_SAFE_INTEGER | Returns the maximum possible safe integer value in JavaScript which is 253 – 1 |
Number.MAX_VALUE | Returns the largest positive representable number |
Number.MIN_SAFE_INTEGER | Returns the minimum possible safe integer value in JavaScript which is -(253 – 1) |
Number.MIN_VALUE | Return the minimum representable numerical value possible in JavaScript. |
Number.NaN | It represents the special “Not a Number” value |
Number.NEGATIVE_INFINITY | It represents the value of Negative Infinity. |
Number.POSITIVE_INFINITY | It represents the value of Negative Infinity. |
Number.prototype | This can be used to add more properties to the Number object |
NOTE: Any value larger than the MAX_SAFE_INTEGER
value will get corrupted when processed in JavaScript.
Let’s take an example to see some of these properties in action.
// Range of Number
document.write(Number.MIN_VALUE+"<br>")
document.write(Number.MAX_VALUE+"<br>")
document.write(Number.NEGATIVE_INFINITY+"<br>")
document.write(Number.POSITIVE_INFINITY+"<br>")
document.write(Number.prototype+"<br>")
document.write(Number.MIN_SAFE_INTEGER+"<br>")
document.write(Number.MAX_SAFE_INTEGER+"<br>")
5e-324 1.7976931348623157e+308 -Infinity Infinity 0 -9007199254740991 9007199254740991
JavaScript Number Object Methods
JavaScript Number object has both static methods(used without any Number object created) and instance methods(used on the object). Following are the most commonly used methods of the Number object:
Method name | Description |
---|---|
Number.isNaN() | Static method; used to check whether the given value is NaN or not. |
Number.isFinite() | Static method; used to check whether the given value is a finite number or not. |
Number.isInteger() | Static method; used to check whether the given value is an integer number or not. |
Number.isSafeInteger() | Static method; used to check if the given value is a safe value or not, i.e. between 253 – 1 to -(253 – 1) |
Number.parseFloat(string) | Static method; used to convert a string to a floating-point number. |
Number.parseInt(string, [radix]) | Static method; used to convert a string to an integer. Here radix represents the base in mathematical numeral systems. |
valueOf() | Returns the primitive value of the Number object. |
toString() | Returns a String value of number object. |
toFixed(x) | Rounds up a number to x digits after the decimal. |
toPrecision(x) | Rounds up a number to a length of x digits. |
toExponential(x) | Converts a number into an Exponential notation. |
Let’s take a few examples to see some of these functions in action.
Convert Number Object to Primitive
The Number object provides a method valueOf()
which can be used to convert the Number object to a primitive type.
let x = new Number(290.78);
document.write(typeof x + "<br/>");
// Conversion from object to number
let num = x.valueOf()
document.write(typeof num + "<br/>");
object number
Using Number in Non-Constructor Context
As we mentioned in the beginning that if we use Number function without the new
keyword, we can use it for type conversion. So let’s see a few examples for it:
// using the Date object
let d = new Date('December 17, 1995 03:24:00');
console.log(Number(d)); // Logs: 819199440000
The above code will give output 819199440000 which is the UNIX timestamp equivalent of the date specified. So the date is successfully converted into a number.
Also, we can use the Number function for simpler conversions like below:
Number('77'); // 77
Number('70.7'); // 70.7
Number(''); // 0
Number('foo'); // NaN
Number('-Infinity'); // -Infinity
Number(null); // 0
JavaScript Number Object Example
In this example, we are using Built-in methods to understand their uses.
<html>
<head>
<title>Using Number Object</title>
</head>
<body>
<script type="text/javaScript">
let num = new Number('18.907');
document.write(num.toExponential() +"<br/>");
document.write(num.toFixed() +"<br/>");
document.write(num.toPrecision(3) +"<br/>");
document.write(typeof num.toString() +"<br/>");
document.write(num.valueOf() +"<br/>");
</script>
</body>
</html>
You can use the Number object for checking the type of any value, for example, if you have to verify if a given value is a number or not, you can use the Number.isNaN
method. Similarly, you can also use the Number object properties to assign MAX and MIN allowed value in your script.
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