Numbers

JavaScript numbers are always stored as double precision (64-bit) floating point numbers.
There is no distinction between integers and decimals.

var myInteger = 20; 
var myDecimal = 5.55; 

Data Types

Check if a value is a number or not

isNumber()
NaN()
parseFloat()

1 == "1"     // true 
1 === "1"   // false 
100 + "25"    // 10025 
"text" + 1    // text 1 

var v1 = 1   // integer 
var v2 = 2.5   // floating point 
var v3 = 070   // integer (in octal, 0 prefix) 
var v4 = 0xffff   // integer (in hex, 0x prefix) 
var v5 = 1.34e5   // scientific 

All numbers are floating point
so decimal fractions are not exact.
standard operators +, -, *, /, %
parseFloat - converts a string to a number

number value Data Type

Number Object

Methods

toFixed(n) - returns the number to n decimal places

let number1 = parseInt("11 two 33"); 
let number2 = parseFloat("22 three 44"); 
let number3 = 11.234.toFixed(0); 
let number4 = 100.6.toFixed(2); 

Number Function

The Number() function converts the object argument to a number that represents the objects value.
If the argument is a Date object, this function returns the number of milliseconds since midnight 1 Jan 1970 UTC.