How to make decisions with if/else

Updated September 2026 · Beginner-friendly guide

Use if and else

The if block runs when its condition is truthy; otherwise the else block runs.

const age = 17;
if (age >= 18) {
  console.log("Adult ticket");
} else {
  console.log("Youth ticket");
}

Test several cases

Place the most specific conditions first. Only the first matching branch runs.

const score = 82;
if (score >= 90) {
  console.log("Excellent");
} else if (score >= 70) {
  console.log("Passed");
} else {
  console.log("Keep practicing");
}

Use a conditional expression

The ternary operator is useful for choosing one of two values. Use normal branches when logic needs several statements.

const isOnline = true;
const label = isOnline ? "Available" : "Offline";
console.log(label);

Write dependable conditions

Use braces even for a one-line branch
Prefer strict equality
Name complex conditions before testing them
Handle boundary values such as exactly 18 or an empty input