Expressions

Expression vs Statement

Understanding the difference between expressions and statements is one of those things that clicks once and changes how you read code.

• Expression — produces a value. 5 + 3, "hello", fn()
• Statement — performs an action. if (...), for (...), let x = ...

An expression can be used anywhere a value is expected. A statement cannot — you can't pass an if to a function.

// Expression: produces a value
5 + 3
"hello".toUpperCase()
Math.max(10, 20)

// Statement: performs an action
let result = 5 + 3;
if (result > 5) {
  console.log("Bigger than 5");
}

// Function expression (expression used where a statement might go)
const add = function(a, b) {
  return a + b;
};
console.log(add(2, 3));