左侧内容COPY右边框框里面

[a20817300]

代码如下<form>
<input type="text" name=s1 id="s1">
<input type=button onclick=copy() value=copy> <input type="text" name=s2>

</form>

[豆虫]

function copy(){
  document.getElementById('s2').value = document.getElementById('s1').value
}

<form>

<input type="text" name="s1" id="s1">
<input type="button" onclick="copy()" value="copy"> <input type="text" name="s2" id="s2">

</form>