Conditionals: if/else and switch

JavaScript branches execution using if/else if/else, the ternary operator, and switch.

const hour = 14;
if (hour < 12) {
  console.log("Morning");
} else if (hour < 18) {
  console.log("Afternoon");
} else {
  console.log("Evening");
}

const label = hour < 12 ? "AM" : "PM"; // ternary operator

switch (hour) {
  case 0:
  case 12:
    console.log("Noon or midnight");
    break;
  default:
    console.log("Some other hour");
}

The ternary operator (condition ? a : b) is a compact expression form of if/else, useful when you need a value rather than a statement — for example, directly inside JSX or a template literal.

switch compares using strict equality internally. Forgetting break causes execution to "fall through" into the next case — sometimes intentional (stacking cases like case 0: and case 12: above), but usually a bug.