为什么无法用JavaScript给DOM设置事件?

 <!DOCTYPE html>
<html>
<head>
    <title></title>
    <meta charset="utf-8">
</head>
<body>
<table id="thisTable">
  <tr>
    <td>id</td>
    <td>name</td>
    <td>age</td>
  </tr>
  <tr>
    <td>001</td>
    <td><input value="Laowang" /></td>
    <td>10</td>
  </tr>
  <tr>
    <td>002</td>
    <td><input value="Yan"/></td>
    <td>9</td>
  </tr>
  <tr>
    <td>003</td>
    <td><input value="Guanyu"/></td>
    <td>9</td>
  </tr>
</table>
</body>
<script type="text/javascript">
window.onload=function(){
    var thisTable = document.getElementById("thisTable");
    var inputs = document.getElementsByTagName("input");
    for(var i=0;i<inputs.length;i++){
        var input = inputs[i];
        input.style="border:0px";
        input.readOnly="true";
        input.onClick="mod()";
        console.log(input);
    }
}
function mod(){
    console.log(111);
}

</script>
</html>

dom.setAttribute("onclick","fun1(this)");

onClick不是属性不是这样添加的

input.onclick = mod;

    function mod(){

alert("hello");
}

document.getElementById("txtPrice").attachEvent('onclick', function (){alert('添加事件成功！')});

///input.onClick="mod()";
///===>
  input.onclick = mod