Hello, console!

The console is where JavaScript prints messages — invisible to normal visitors, indispensable to developers. Every browser has one built in (try pressing F12 sometime!). Our playgrounds show it right below the code.

console.log — your printing press

Three observations:

• Text needs quotes; math doesn't.
• Comma-separated values print with spaces between them.
• Instructions run top to bottom, in order.

Anatomy of the line

console.log("Hello!");

• console — a built-in object representing the console
• .log — the method (action) we're calling on it
• ("Hello!") — what we hand to it
• ; — the period at the end of a JavaScript sentence

Comments

Notes for humans, ignored by JavaScript:

What's next

Values, expressions, and what happens when things go wrong — learning to read errors while they're still tiny.