Swap a "main" image by hovering over a thumb image.

swapmainimg.js

// Swap a "main" image by hovering over a thumb image.
// They both need to have the same scr, except for the "template" part.

$(function () {

	$( '.thumbimg' ).each( function (i) {
		$( this ).on({
			mouseenter: function() {
				$('#mainimg').attr(
					'src',
					$( this ).attr('src').replace('fit164x164', 'fit555x555') // Replace the template part in the src
				);
			}
		});
	});
	
});