resize的操作

(function() {
  var fn = function() {
    var w = document.documentElement
        ? document.documentElement.clientWidth
        : document.body.clientWidth,
      r = 1255,
      b = Element.extend(document.body),
      classname = b.className;
    if (w < r) {
      //当窗体的宽度小于1255的时候执行相应的操作
    } else {
      //当窗体的宽度大于1255的时候执行相应的操作
    }
  };
  if (window.addEventListener) {
    window.addEventListener("resize", function() {
      fn();
    });
  } else if (window.attachEvent) {
    window.attachEvent("onresize", function() {
      fn();
    });
  }
  fn();
})();