console.log and comments

The language of the web

• JavaScript runs inside every web browser. It makes pages do things — buttons, games, maps, chat.
• console.log(...) prints a message to the console, a window for text output.
• Anything after // is a comment. JavaScript ignores it — it is a note for humans reading the code.

console.log("Hello, world!");   // → Hello, world!
// this whole line is a comment — it does nothing

Print text, numbers, or both

• Text goes inside quotes: "hello". Numbers do not: 42.
• Pass several items separated by commas — they print on one line, with a space between.

console.log("Score:", 42);   // → Score: 42
console.log(3 + 4);          // → 7

Watch out

• Text needs quotes. console.log(Hello) is an error — JavaScript hunts for something named Hello.
• End each statement with a semicolon ;. It is a good habit, even where JavaScript would forgive you.

Common mistakes

• console.log(...) prints; text needs quotes.
• // starts a comment.

Now you try

• Use console.log(...) to print.
• Press Run to see the output, then Check answer.