点击不同按钮，输入不同内容到输入框

<p><textarea id="tc_url" rows="3" cols="35" name="tc_url"></textarea></p>
 <button value ="我是1">1</button>
 <button value ="我是2">2</button>
 <button value ="我是3">3</button>
 <button value ="我是4">4</button>
 <button value ="我是5">5</button>
 <button value ="我是6">6</button>
 <button value ="我是7">7</button>
 <button value ="我是8">8</button>

<script type="text/javascript">
 window.onload=function(){
 var ts=document.getElementsByTagName("button");
    for(var i=0;i<ts.length;i++){
        ts[i].onclick=function(){
 document.getElementById("tc_url").value = this.value;
}}}

</script>