function getImage(){

	image = new Array(15); //定义image为图片数量的数组

	image [0] = 'images/header/image1.jpg' //背景图象的路径

	image [1] = 'images/header/image2.jpg'

	image [2] = 'images/header/image3.jpg'

	image [3] = 'images/header/image4.jpg'

	image [4] = 'images/header/image5.jpg'

	image [5] = 'images/header/image6.jpg'

	image [6] = 'images/header/image7.jpg'

	image [7] = 'images/header/image8.jpg'

	image [8] = 'images/header/image9.jpg'

	image [9] = 'images/header/image10.jpg'

	image [10] = 'images/header/image11.jpg'

	image [11] = 'images/header/image12.jpg'

	image [12] = 'images/header/image13.jpg'

	image [13] = 'images/header/image14.jpg'

	image [14] = 'images/header/image15.jpg'

	image [15] = 'images/header/image16.jpg'

	number = Math.floor(Math.random() * image.length);

	document.getElementById("header").style.background="url("+image[number]+")";

}