Numbers

Unlike many other programming languages, JavaScript does not define different types of numbers, like: integers, short, long, floating-point, etc. Instead, JavaScript incorporates a wide variety of numberic literals available for the developer. To learn more, click here.

Precision

Integers (numbers WITHOUT a period exponent notation) are accurate up to 15 digits.

var precise = 999999999999999;   // precise will be 999999999999999
var rounded = 9999999999999999;  // rounded will be 10000000000000000

The maximum decimal places for any given number is 17, however floating point arithmetic is not always fully accurate.

var closeButNoCigar = 0.2 + 01; // closeButNoCigar will be 0.30000000000000004

To solve this precision problem, it helps to multiply each value, and then divide.

var numbersAreHard = (0.2 * 10 + 0.1 * 10) / 10; // numbersAreHard will be 0.3!

Numbers Vs. Strings

JavaScript uses the + operator for both addition of numbers and concatenation for strings.

// numbers

var numberOne = 10;
var numberTwo = 20;
var addition = numberOne + numberTwo // addition will be 30

// strings

var stringOne = '10';
var stringTwo = '20';
var concat = stringOne + stringTwo // concat will be '1020'

The value within a string are NOT interpreted by JS; if you have numbers within a string that you want to add, be aware that JS will simply concat, or slam the two values side by side, rather than perform the necessary math.

Number Object

JavaScript has a built in number object that has properties for numberical constants (maximum, value, NaN, infinity, etc.). You cannot change the values of these properties.

// Number objects

Number.MAX_VALUE // The largest representable number
Number.MIN_VALUE // The smallest representable number
Number.NaN // Special 'not a number' value
Number.NEGATIVE_INFINITY // Special negative infinite value; returned on overflow
Number.POSITIVE_INFINITY // Special positive infinite value; return on overflow
Number.EPSILON // Difference between one and the smallest value greater than one that can be represented as a Number
Number.MIN_SAFE_INTEGER // Minimum safe integer in JS
Number.MAX_SAFE_INTEGER // Maximum safe integer in JS

// Number methods

Number.parseFloat() // Parses a string argument and returns a floating point number 
Number.parseInt() // Parses a string argument and returns an integer of the specified radix or base
Number.isFinite() // Determines whether the passed value is a finite number
Number.isInteger() // Determines whether the passed value is an integer
Number.isNaN() // Determines whether the passed value is NaN
Number.isSafeInteger() // Determines whether the provided value is a number that is a safe integer

// Number prototypes

Number.prototype.toExponential() // Returns a string representing the number in exponential notation
Number.prototype.toFixed() // Returns a string representing the number in fixed-point notation
Number.prototype.toPrecision() //Returns a string representing the number to a specified precision in fixed-point notation