see below is my javascript,

<script type=text/javascript>

document.getElementById('auth').onclick=change;

function change(){

    this.className=account_holder;

}

</script>

html is

<td id=auth class=authorised_reportericon >

                        <a href={% url incident.views.authorised_reporter %}>

                        <p align=center style=color:black;font-size:16px;>Authorised Reporters</p></a>

                    </td>

I assigned td's id for onclick,but it is trowing error as Uncaught TypeError: Cannot set property 'onclick' of null