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JavaScript

Operators and Expressions

Easy
15 min

What Is an Expression?

An expression is a piece of code that produces a value. Think of it like a little math problem that JavaScript solves for you. When you write an expression, JavaScript evaluates it and gives you an answer. For example:

5 + 3

This expression uses the addition operator (+) to combine the numbers 5 and 3. When evaluated, it gives the value 8.

Arithmetic Operators

Arithmetic operators let you perform basic math calculations. The most common ones are:

  • Addition (+): Combines two numbers.
    Example: 5 + 3 gives 8.
  • Subtraction (-): Finds the difference between two numbers.
    Example: 10 - 4 gives 6.
  • Multiplication (*): Multiplies two numbers.
    Example: 4 * 2 gives 8.
  • Division (/): Divides one number by another.
    Example: 20 / 5 gives 4.
  • Remainder (%): Gives the remainder after division.
    Example: 7 % 3 gives 1.

Combining Operators in Expressions

You can combine values and operators to build more complex expressions. For instance, if you write:

(10 + 5) * 2

JavaScript first calculates the expression in parentheses (10 + 5 equals 15), and then multiplies that result by 2, giving 30.

Using Expressions with Variables

Often, you’ll use expressions with variables to update values. For example:

let counter = 0;
counter = counter + 1;
console.log(counter);

Here, the expression counter + 1 adds 1 to the current value of counter, and then we update counter with the new value.

Exercises

Simple Addition

  • Write an expression that adds 5 and 3 together
  • Store the result in a variable called result using let.
  • Print result using console.log(result).

Combining Multiple Operators

  • Create an expression that calculates the result of (8 * 2) - (10 / 2).
  • Store the answer in a variable called calculation using let.
  • Print the value of calculation with console.log(calculation).

Updating a Counter

  • Create a variable called counter using let and initialize it to 0.
  • Update the variable by adding 1 to it using an expression.
  • Print the updated value using console.log(counter).
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