JavaScript Numbers

Javascript numbers are primitive data types. Unlike other programming languages, you don’t need int, float, etc to declare different numeric values. JavaScript numbers are always stored in double-precision 64-bit binary format IEEE 754. 

This format stores numbers in 64 bits, 

• 0-51 bit stores value(fraction)
• 52-62 bit stores exponent
• 63-bit stores sign

Example:

Javascript

<p id="demo"></p>

<script>
    let x = 5; // Declaration
    document.getElementById("demo").innerHTML = x;
</script>

Output:

5

Number Literals: The types of number literals You can use decimal, binary, octal, and hexadecimal.

Decimal Numbers: JavaScript Numbers does not have different types of numbers(ex: int, float, long, short) which other programming languages do. It has only one type of number and it can hold both with or without decimal values.

Var a=33;
var b=3.3;
var x = 0562   // x will be 370(parsed as an octal number).

If the number starts with 0 and the following number is smaller than 8. It will be parsed as an Octal Number. Integers are accurate up to 15 digits: 

var a = 999999999999999;      // a will be 999999999999999
var b = 9999999999999999;    // b will be 10000000000000000

The floating point is not 100% accurate. The maximum number of decimals is up to 17.

var x = 0.22 + 0.12;   //x will be 0.33999999999999997

Example 1:

Javascript

<p id="num"></p>

<script>
    var x = 0.22 + 0.12;
    document.getElementById("num").innerHTML =
        "0.22 + 0.12 = " + x;
</script>

Output:

0.22 + 0.12 = 0.33999999999999997

Binary Numbers: They start with 0b or 0B followed by 0’s and 1’s. 

var x = 0b11;        // x will be 3
var x = 0B0111;    // x will be 7

Example 2:

Javascript

<p id="num"></p>
<script>
    var x = 0B0111;
    document.getElementById("num").innerHTML =
        "0B0111 will be " + x;
</script>

Output:

0B0111 will be 7

Octal Numbers: They start with 0 followed by a number of ranges from 0-7. If any number is used it will be taken as a decimal number. 

var x = 0111;       // x will be 73
var x = 07123;     // x will be 3667

Example 3:

Javascript

<p id="num"></p>
<script>
    var x = 07123;
    document.getElementById("num").innerHTML =
    "07123 will be " + x;
</script>

Output:

07123 will be 3667

Hexadecimal Numbers: They start with 0x or 0X followed by any digit belonging (0123456789ABCDEF) 

var x = 0xfff;   // x will be 4095

Example 2:

Javascript

<p id='num'></p>
<script>
    var x = 0xfff;
    document.getElementById(
        "num").innerHTML =
        "0xfff will be " + x;
</script>

Output:

0xfff will be 4095

Exponentiation:

var x = 2E5     // x will be 200000
var x = 34e3   // x will be 34000
var x = 23e-5  // x will be 0.00023

JavaScript uses the + operator for both addition and concatenation. 

Addition:

var a = 20;
var b = 20;
var c = a + b;           // c will be 40 (a number)

Concatenation:

var a = "10";
var b = "20";
var c = a + b;           // c will be 1020 (a string)

Numeric Strings:

• In javascript, strings can take numeric values as well. It converts strings to numbers in every operation.
• NaN is a reserved word indicating not a number.

 var x= "12345" ;    // x will be a string(NaN)   
 var x = 67 ;            // x will be number

Some facts about numbers in JavaScript:

• If you add a string and number, there will be a string concatenation as an output.
• Javascript numbers which are primarily primitive values can also be defined as objects using a new keyword.
• Constants preceded by 0x are interpreted as hexadecimal in javascript.   
• Javascript numbers are of base 10 by default, but we can use the toString() method to get output in the required base from base 2 to base 36.
• Apart from regular numbers, Javascript has BigInt numbers which are integers of arbitrary length. Regular integer numbers can’t safely exceed (253-1) or be less than -(253-1) that’s when BigInt serves the purpose.

Reference: https://www.geeksforgeeks.org/javascript-number-complete-reference/