function randomImage() {
	// Images should be named like this: imageNameRoot + number + imageType. For example, if
	// imageNameRoot = 'headerImage_', then an image might be named 'headerImage_4.jpg'. This script
	// builds a random file name based on the config params below.
	//
	// Afterwards, we find the container for the element and insert the new image into it.

	// CONFIG
	// How many images?
	var imageQuantity = 7;
	// Where are they?
	var imageDirectory = 'images/';
	// What is the base of the file names of the images?
	var imageNameRoot = 'headerImage_';
	// What's the file extension (not including the '.')?
	var imageType = 'jpg';
	
	// Create a new array to contain all the images:
	var randomImage = new Image();
	// Create a random number:
	var randomNumber = Math.floor(Math.random()*imageQuantity+1);
	// Set the .src property of the image to the path to the file:
	randomImage.src = imageDirectory + imageNameRoot + randomNumber + '.' + imageType;

	// Get a reference to the container of the image we'd like to swap:
	var randomImageContainer = document.getElementById('random_image');
	// Then create an image inside it:
	randomImageContainer.appendChild(randomImage);
}