Internet explorer 8 form.submit（）在IE8中不起作用-“类未注册”

有人知道为什么这个函数的最后一行form.submit在IE8中抛出一个类not registered错误吗

//capture the map dimensions and submit the form to fetch a GPX file   
GMap2.prototype.downloadGPX = function(input) {
  var form = input.parentNode;
  form.swx.value = this.getBounds().getSouthWest().x
  form.swy.value = this.getBounds().getSouthWest().y
  form.nex.value = this.getBounds().getNorthEast().x
  form.ney.value = this.getBounds().getNorthEast().y
  form.zoom.value = this.getZoom();
  form.submit();
}

---

这不起作用的原因是我设置了form.target，而您不能在IE8中使用.target