Basic Operators

Mathematic operations to numbers can be performed using some basic operators like:

• Addition: c = a + b

• Subtraction: c = a - b

• Multiplication: c = a * b

• Division: c = a / b

The JavaScript interpreter works from left to right. One can use parentheses just like in math to separate and group expressions: c = (a / b) + d

JavaScript uses the + operator for both addition and concatenation. Numbers are added whereas strings are concatenated.

NaN is a reserved word indicating that a number is not a legal number, this arises when we perform arithmetic with a non-numeric string will result in NaN (Not a Number).

let x = 100 / "10";

The parseInt method parses a value as a string and returns the first integer.

parseInt("10"); // 10
parseInt("10.00"); // 10
parseInt("10.33"); // 10
parseInt("34 45 66"); // 34
parseInt(" 60 "); // 60
parseInt("40 years"); //40 
parseInt("He was 40"); //NaN

In JavaScript, if we calculate a number outside the largest possible number it returns Infinity .

let x =  2 / 0; // Infinity
let y = -2 / 0; // -Infinity