First, why are you worried about the index of the item you're editing? Seems weird given the nature of
EditFor
.
Don't do it on the client side. Do it this way:
@foreach(var item in Model)
{
@* if you really need the index, you can do this in a foreach loop *@
int index = Model.IndexOf(item);
<tr>
<td>
@Html.EditFor(m=>m.strengthC[index],...)
...
</td>
</tr>
}