if / else

Making decisions

• if (test) { ... } runs its block only when the test is true.
• else gives the path to take when the test is false.

let age = 20;
if (age >= 18) {
  console.log("adult");   // → adult
} else {
  console.log("minor");
}

Many paths with else if

• Add else if for more choices. JavaScript checks each test top to bottom.
• The first test that is true wins; the rest are skipped.

let mark = 72;
if (mark >= 70) {
  console.log("A");        // → A
} else if (mark >= 50) {
  console.log("B");
} else {
  console.log("C");
}

Watch out

• Put the test in ( ) and the block in { }.
• Inside a test, compare with === (day === "Sat"), never a single =.

Common mistakes

• The condition goes in ( ) and the body in { }.
• Compare with ===.

Now you try

• Read the value, then choose with if / else.
• Press Check answer to test it.