用javascript如何给span赋值呢?一般有两种方法:

1>输出html

<body onload="s()">
<span id="hello"></span><script language="javascript">
  function s(){
document.getElementById("hello").innerHTML = "<iframe src=  height=400 width=300></iframe>";}
  </script>

2>输出文本

<body onload="s()">
<span id="hello"></span><script language="javascript">
  function s(){
document.getElementById("hello").innerText = "hello world";}
</script>