Operations & Expressions In JavaScript

Have you ever wondered how your programs handle calculations, compare values, and decide what to do next? The secret is in the operators — those little tools that make your code work.

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In this guide, you’ll get a clear look at JavaScript’s expressions and operators. You’ll see what they do, how they interact, and why they’re so important. We’ll cover arithmetic, assignment, comparison, logical, bitwise, string, conditional (ternary), comma, unary, and relational operators, along with some details about operator precedence and associativity.

In JavaScript, an expression is any piece of code that produces a value. It might be as straightforward as a single number or variable, or it might be a mix of values, variables, and operators.
Operators are the symbols or keywords that tell JavaScript to perform an action—whether that’s adding numbers, comparing values, or evaluating a condition.

You’ll work with two kinds of expressions. Some not only produce a value but also create a side effect, like when you write y = 10(which both returns 10 and assigns that value tox). Others just compute a value, like 4 + 6, which gives you 10 that might go unused if you don’t store or use it.

Knowing how to build and evaluate expressions is essential for writing code that behaves the way you expect.