Basic JavaScript: Variables and Functions

JavaScript makes a page respond to things instead of just sitting there. Like CSS, it deserves its own full handbook, but here are the basics you need.

A variable stores information so you can use it later. In modern JavaScript, you create one using let or const. A function is a reusable block of code that runs when you call it.

let visitorName = "friend";


function greetVisitor() {

  console.log("Welcome, " + visitorName + "!");

}


greetVisitor();

Explanation:

• visitorName is a variable holding a piece of text.
• greetVisitor is a function that, when invoked (called), prints a welcome message using that variable. The last line actually runs the function. Without calling it, the function would just sit there doing nothing.