If/Else (Conditionals)

An if/else is a fork in the road for your code. Picture a bouncer at a door. IF you are old enough, they let you in. ELSE, they turn you away. The computer checks a yes/no question, called a 'condition'. Then it runs different code depending on the answer.

1. 1Write `if` followed by a question that is true or false, like 'is the temperature below 0?'.
2. 2If the answer is true, the code inside that block runs. If it's false, the computer skips to the next check.
3. 3Add `else if` for more questions. Add a final `else` to catch 'none of the above'.

Use if/else whenever your program needs to make a decision. It can do different things depending on the situation. For example, show an error if a field is empty, or give a discount if a cart total is high enough.

• ⚠Using `=` (which sets a value) instead of `==` or `===` (which checks if two values are equal) inside a condition.
• ⚠Writing conditions in the wrong order. If you check the broad case before the narrow one, the narrow one never runs.