Javascript Numbers:

JavaScript has specific type of numbers, which can easily be written with or without decimals. The number (value) transforms a string or other component to the number type.

Example:

var x = 2.76;    // A number with decimals
var y = 2;       // A number without decimals

We can write huge values or extra small values with exponent notation.

Example:

var x = 123e5;    // 12300000
var y = 123e-5;   // 0.00123

Numbers in javascript are always 64-bit floating point:

• JavaScript does not determine dissimilar types of numerals like small, huge, floating-point, integers etc.
• JavaScript numerals are always saved double accuracy floating-point numerals.
• It accompanies the international IEEE standard.
• This arrangement saves numerals in 64 bits whereas, the numeral is saved in bits 0 to 51, the component in bits 52 to 62, and the sign in bit 63:

Precision

Whole numbers are precise up to 15 numbers.

EXAMPLE:

var x = 999999999999999;   // x will be 999999999999999
var y = 9999999999999999;  // y will be 10000000000000000

The highest number of digits is 17, but floating-point arithmetic is not usually 100% precise.

Example:

var x = 0.4 + 0.2;         // x will be 0.60000000000000001

It also helps to multiply and divide to simplify the difficulty above:

Example:

var x = (0.4 * 10 + 0.2 * 10) / 10;       // x will be 0.6

ADDING NUMBERS AND STRINGS

Addition of two numbers will always return a number.

Example:

var x = 30;
var y = 40;
var z = x + y;           // z will be 70 (a number)

Addition of two strings will proceed an answer that will be a string concatenation.

EXAMPLE:

var x = "30";
var y = "40";
var z = x + y;           // z will be 3040 (a string)

Addition of number and string will proceed a result in string concatenation.

Example:

var x = 30;
var y = "40";
var z = x + y;           // z will be 3040 (a string)

Addition of string and number will proceed a result in string concatenation.

EXAMPLE:

var x = "30";
var y = 40;
var z = x + y;           // z will be 3040 (a string)

There can be a few misunderstandings related to concatenation in Javascipt. Let's have a look:

EXAMPLE:

var x = 30;
var y = 40;
var z = "The result is: " + x + y;

A usual misunderstanding is to expect the above answer to be 70.

EXAMPLE:

var x = 30;
var y = 40;
var z = "10";
var result = x + y + z;

Another misunderstanding can be to expect the above code to return 304010.

NOTE:

• The JavaScript exponent runs from left side to the right side.
• We added 30 + 40 first because x and y are both numerals.
• Z is a string, that’s why 30 + "30" is concatenated.
• The + operator is applied to concatenate the strings.

Numeric Strings

JavaScript strings also includes numeral content.

var x = 200;         // x is a number
var y = "200";       // y is a string

This is how JavaScript transforms strings to numerals in all numeric operations:

var x = "200";
var y = "20";
var z = x / y;       // z will be 10

NaN (NOT A NUMBER)

• NaN indicates that a number is an unauthorized number.
• Solving with a non-numeric string will display the answer in NaN.

Example:

var x = 200 / "Orange";  // x will be NaN (Not a Number)

But, if the string consists of a digit, the result will be a numeral:

Example:

var x = 200 / "20";     // x will be 10

The use of global JavaScript function isNaN() is very efficient to determine whether the value is a number:

Example:

var x = 200 / "Apple";
isNaN(x);               // returns true because x is Not a Number

Moreover, if you use NaN in calculation it will display the answer NaN.

Example:

var x = NaN;
var y = 7;
var z = x + y;         // z will be NaN

The result can be concatenated:

Example:

var x = NaN;
var y = "7";
var z = x + y;         // z will be NaN7

NaN is a numeral: typeof NaN restores number:

Example:

typeof NaN;            // returns "number"

INFINITY

Infinity is the digit JavaScript will return if you compute a numeral greater than the largest viable number, let’s take an example.

Example:

var myNumber = 3;
while (myNumber != Infinity) {   // Execute until Infinity
  myNumber = myNumber * myNumber;
}

Dividing numerals by 0 (zero) also results in infinity:

Example:

var x =  3 / 0;       // x will be Infinity
var y = -3 / 0;       // y will be –Infinity

Infinity is a numerical value however, typeof Infinity restores number.

Example:

typeof Infinity;     // returns "number"