php - how refresh image name automatically using javascript -

hello use script simpleimage

		// making simpleimage instances of selected friends including main image  		$img = new abeautifulsite\simpleimage('main.jpg');  		//$img1 = new abeautifulsite\simpleimage($friend1);  		//$img2 = new abeautifulsite\simpleimage($friend2);  		//$img3 = new abeautifulsite\simpleimage($friend3);

how refresh image name main.jpg automatically after refresh page using javascript or jquery ?

i tried tutorial jquery div auto load , refresh

this variable placed somewhere image <?php echo $bg_array[$bg];?> did not work

all want update main.jpg every time page loaded