Defining Functions

You're on a roll!

OK, now we've gotten familiar with JavaScript variables and values, let's get down to the real business, functions.

Here is the definition of a function called plusOne that adds one to its argument.

// A simple function that adds one var plusOne = function (x) { return x + 1; };

Here's code that uses the function to set the value of y.

var y = plusOne(10);

The variable y is set to 11, because 10 + 1 is 11.

Functions can take more than one argument. Here is a function that takes two arguments.

// Calculate the area of a rectangle var area = function (w, h) { return w * h; };

Define a function named add that takes two arguments x and y, and returns the sum of x and y.