Change an image when the mouse moves onto it, and then back to the original image when the mouse moves off of it javascript code example

Example: javascript swap images on mouseover

function rollover(my_image)
		{
	
			my_image.src = 'images/costAnalysisBtn2.png';
	
		}
function mouseaway(my_image)
		{
	
			my_image.src = "images/costAnalysisBtn1.png";
	
		}
onmouseover="rollover(this)" onmouseout="mouseaway(this)"