Making Decisions With if and else

Making Decisions With if and else

In this lesson, you ported the crew’s decision about one dock, empty, nearly full or fine, from Python’s if, elif and else to JavaScript.

• The condition goes in parentheses, and the block goes in braces, where Python uses a colon and indentation: if (bikes === 0) {.
• JavaScript doesn’t read indentation. The braces mark where a block starts and stops, and the indentation inside them is only for you: scramble it, and the chain still prints Harbor Square is nearly full. Always write the braces. The full story comes later.
• JavaScript compares with ===, called strict equality. It has a two-sign version as well, and why you leave that one alone is a later topic.
• There’s no elif: JavaScript writes else if, an else followed by a second if, right after the closing brace. The last else gets braces and no colon.
• JavaScript spells and, or and not with symbols, the logical operators &&, || and !. Carry the word or across, and JavaScript stops with a SyntaxError before any of the file runs.

Here’s the crew’s Python script for Station Road:

name = "Station Road"
bikes = 6
slots = 8

if bikes == 0:
    print(f"{name} is empty")
elif slots <= 2:
    print(f"{name} is nearly full")
else:
    print(f"{name} is fine")

if bikes == 0 or slots <= 2:
    print(f"The van stops at {name}")

if bikes > 0 and slots > 2:
    print(f"The van can skip {name}")