OnClick of disabled textbox raise event

<div onclick="aa()" style="cursor:z-index:8; display:block; width: 143px; height:20px; background-color: trasparent; position:absolute"></div>
   <input type="text" readonly="readonly" value="demo test">

function aa()
{
    alert("oye hoyee... textbox click ho gaya :) ");
}