Page 65 - JavaScript

false + 5; // 5
null + 1; // 1
undefined + 1; // NaN

If a boolean value is given alongside a string value, the boolean value is converted to a string
instead:

true + "1"; // "true1"
false + "bar"; // "falsebar"

Subtraction (-)

The subtraction operator (-) subtracts numbers.

var a = 9;
var b = 3;
var c = a - b;

c will now be 6

If a string or boolean is provided in place of a number value, it gets converted to a number before
the difference is calculated (0 for false, 1 for true):

"5" - 1; // 4
7 - "3"; // 4
"5" - true; // 4

If the string value cannot be converted into a Number, the result will be NaN:

"foo" - 1; // NaN
100 - "bar"; // NaN

Multiplication (*)

The multiplication operator (*) perform arithmetic multiplication on numbers (literals or variables).

console.log( 3 * 5); // 15
console.log(-3 * 5); // -15
console.log( 3 * -5); // -15
console.log(-3 * -5); // 15

Division (/)

The division operator (/) perform arithmetic division on numbers (literals or variables).

console.log(15 / 3); // 5
console.log(15 / 4); // 3.75

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