javascript兼容所有浏览器绑定和删除事件处理函数代码

<script>
function bind(target, type, func) {  if (target.addEventListener) {
    target.addEventListener(type, func, false);
  } 
  else if (target.attachEvent) {
    target.attachEvent("on" + type, func);
  } 
  else {
    target["on" + type] = func;
  }
}
  
function unbind(target, type, func) {
  if (target.removeEventListener) {
    target.removeEventListener(type, func, false);
  } 
  else if (target.detachEvent) {
    target.detachEvent("on" + type, func);
  } 
  else {
    target["on" + type] = null;
  }
}
</script>