I can think of a few hacky ways, but for example below in my doSomething method, how can i determine the rowIndex?
<tr ng-repeat="a in mydata">
<td><b>{{doSomething(mydata.name)}}</b></td>
<td>{{age}}</td>
<td>hello</td>
</tr>
ng-repeat provides properties $first, $index, $middle, and $last. Since in the title question you asked about the first row, you could pass $first as a boolean:
<tr ng-repeat="a in mydata">
<td><b>{{doSomething($first)}}</b></td>
<td>{{a.age}}</td>
<td>hello</td>
</tr>
AngularJS automatically includes the magic $index in an ng-repeat. So you can get the row number like so:
<tr ng-repeat="a in mydata">
<td><b>{{doSomething($index)}}</b></td>
<td>{{a.name}}</td>
<td>{{a.age}}</td>
</tr>
