function blackAndWhite () {
  var body = document.body;
  body.style['filter'] = 'progid:DXImageTransform.Microsoft.BasicImage(grayscale=1)';
  if (!body.style['filter']) {
    body.style['-webkit-filter'] = 'grayscale(1)';
    body.style['filter'] = 'grayscale(1)';
  }
}
//逝者安息