Javascript: Function To Check Whether TextField is ReadOnly

The following Javascript function can be used to check whether the given control is read only or not?

Sample 1:

function isReadOnly()
{
var m = document.getElementById("TextBox1").getAttribute("Readonly");
if (m==true)
{
alert('Read Only!');
return true;
}
else
{
alert('Not Read Only');
return false;
}

}

Sample 2:


function isReadOnly(controlID)
{
var m = document.getElementById(controlID).getAttribute("Readonly");

if (m==true)
{
alert('Read Only!');
return true;
}
else
{
alert('Not Read Only');
return false;
}

}