Operators

There are different types of operators in JavaScript. Some operators are unary operators, they work on a single operand. Others are binary operators, they require two operands. There is also a ternary operator in JavaScript. Ternary operators require three operands. Next let's review these operators.

The typeof operator

There is an operator in JavaScript called the typeof operator. It is used to check the data type of a variable. To use it, you specify the name of the variable in parentheses after the keyword as in typeof(variableName). It is a unary operator.

Arithmetic Operators

These operators are used to carry out mathematical operations.

• Addition: The + operator is used to add two numbers together: 16 + 7.
• Subtraction: The - operator subtracts the right number from the left: 9 - 8.
• Multiplication: The * operator multiplies two numbers together: 9 * 5.
• Division: The / operator divides the left number by the right number: 54 / 5.
• Remainder (modulo): The % operator returns the remainder after a division: 18 % 3.
• Exponent: The ** operator, also known as the power operator, raises a base number to the exponent: 3 ** 2 = 9

Activity

Operator Precedence

With respect to the arithmetic operators, the exponent operator has the highest level of precedence. Division / and multiplication * come next, and they have a higher precedence to addition and subtraction (which are both on the same level of precedence). When operators on the same level of precedence are used, the order of execution is from left to right.

Increment and Decrement Operators

JavaScript also has the increment and decrement operators to easily add or subtract one from a numeric value.

Try it in the console:

let x = 9;
let y = 8;
x++;
y--
console.log(x)
console.log(y)

Assignment Operators

Assignment operators are used to assign a value to a variable. We have seen how to use = severally, it assigns the value on the right to the variable on the left. Apart from the basic =, other complex assignment operators exist.

For example, the addition assignment operator, +=, it adds the values on the right to the variable on the left, and assigns the new value to the variable. In like manner, we have the subtraction assignment operator, -=, the multiplication assignment operator, *=, and the division assignment operator, /=.

Try it!

let x = 8;
console.log(x += 8)
console.log(x -= 6)
console.log(x *= 4)
console.log(x /= 2)

Comparison Operators

Similar to the Python programming language, there are several comparison operators in JavaScript that can be used to run true/false tests. They always return one of the two Boolean values: true or false. The code snippet below shows examples

Logical Operators

Logical operators are used to compare Boolean values. JavaScript supports three comparison operators, namely: and, or, and not. They are binary operators, with the exception of the not operator which is a unary operator.

The logical and operator

The && operator represents the logical and. It returns true only if both values given to it are true, otherwise it returns false.

The logical or operator

The || represents logical or. It returns true if any of the operands given to it are true. It only returns false when both operands given to it are false.

The logical not operator

The !, represents the logical not. It simply flips or negates the value given to it.

The conditional operator

The JavaScript language has one ternary operator. A ternary operator is one that operates on three operands (values). It is called the conditional operator. Take a look at the code snippet below to see how it operates.

console.log(true ? "it's true" : "it's false" )
//it's true

console.log(false ? "it's true" : "it's false" )
//it's false

console.log(true ? 1 : 2 )
//Your turn. What do you think the output will

The value on the left of the question mark “picks” which of the other two values will come out. When it is true, it chooses the middle value, and when it is false, it chooses the value on the right.

Activity

👉🏿 Try it: Practice the arithmetic operators by drawing different boxes here.