JS Operators | Robert Samek

JavaScript Arithmetic Operators

There are two types of Arithmetic Operators in JavaScript; Binary and Unary. Binary Operators require two operands; one on each side of the Operator. Unary Operators are pre-pended or appended to a single operand. The examples below explain how each operator is used and display code you can use to evaluate equations using each type.

Binary Operators:

Addition Operator

This is simply a standard addition equation.


		var a = 50;

		var b = 24;

		var solutionValue = a + b;

		document.write("<p>The result of the solutionValue variable after the addtition operator is evaluated is " + solutionValue + "</p>");

Subtraction Operator

This is simply a standard subtraction equation.


		var a = 50;

		var b = 24;

		var solutionValue = a - b;

		document.write("<p>The result of the solutionValue variable after the subtraction operator is evaluated is " + solutionValue + "</p>");

Multiplication Operator

This is simply a standard multiplication equation.


		var a = 50;

		var b = 24;

		var solutionValue = a * b;

		document.write("<p>The result of the solutionValue variable after the multiplication operator is evaluated is " + solutionValue + "</p>");

Division Operator

This is simply a standard division equation, but because 50 is not evenly divisible by 24 you get a remainder.


		var a = 50;

		var b = 24;

		var solutionValue = a / b;

		document.write("<p>The result of the solutionValue variable after the division operator is evaluated is " + solutionValue + "</p>");

Modulus Operator

For those of you who aren’t familiar with Modulus, it’s the reminder after the left operand is divided by the right operand.


		var a = 50;

		var b = 24;

		var solutionValue = a % b;

		document.write("<p>The result of the solutionValue variable after the modulus operator is evaluated is " + solutionValue + "</p>");

Unary Operators:

Increment Operator

The Increment Operator adds an increment of 1 when placed before the variable. It’s denoted by two plus signs.


		var onhandQuantity = 100;

		var newInventory = ++onhandQuantity;

		document.write("<p>"The inventory quantity is now " + newInventory + "</p>");

When placed after the variable, the Increment Operator doesn’t change the variable value until the next iteration. That means that it remains at a value of 100.


		var onhandQuantity = 100;

		var newInventory = onhandQuantity++;

		document.write("<p>"The new inventory quantity is still " + newInventory + "</p>");

Decrement Operator

The Decrement Operator decreases the variable by an increment of 1 when placed before the variable. It’s denoted by two minus signs.


		var onhandQuantity = 100;

		var quantitySold = --onhandQuantity;

		document.write("<p>"The inventory quantity is now " + quantitySold + "</p>");

When placed after the variable, the Decrement Operator doesn’t change the variable value until the next iteration. That means that it remains at a value of 100.


		var onhandQuantity = 100;

		var quantitySold = onhandQuantity--;

		document.write("<p>"The new inventory quantity is still " + quantitySold + "</p>");

Negation Operator

This negation operator negates the value of the variable. It’s denoted by a single minus sign.


		var onhandQuantity = 100;

		var quantitySold = -onhandQuantity;

		document.write("<p>"The inventory quantity is now " + quantitySold + "</p>");

When added to a variable with a negative value, the result is a positive value.


		var onhandQuantity = -100;

		var inventoryAdded = -onhandQuantity;

		document.write("<p>"The inventory quantity is now " + inventoryAdded + "</p>");