How to create subtotals in a ng-repeat in Angular JS - angularjs

Question

I'm just learning AngularJS and need to create the report below. I have all the detail lines working well but have no idea how to create the subtotal lines.
Detail lines...
<tr data-ng-repeat-start="t in testReferrers">
<td>{{t.ReferrerName}}</td>
<td>{{t.AddressLine1}}}</td>
<td>{{t.DatePlaced | date:'MM/dd/yyyy'}}</td>
<td>{{t.InvoiceNumber }}</td>
<td>{{t.InvoiceAmountLessDiscount | currency : $ : 2 }}</td>
</tr>
My first attempt at subtotal line, but I don't know how to calculate {{subTotal}} and how to control when this row shows up. I need a grouping and group footer capability but don't know how to do that in AngularJS. I was going to use JQuery to find the subTotalRow and either show or hide...
<tr id="subtotalRow" data-ng-repeat-end style="display:none">
<td colspan=3></td>
<td style="border-top: solid 1px #000000">Total:</td>
<td style="border-top: solid 1px #000000">{{subTotal | currency : $ : 2 }}</td>
</tr>
Desired output...

Answer 1

angular.module('app', []).controller('ctrl', function($scope){
$scope.data = [
{Referrer: 'Henry', Amount: 20, Location: 'NY'},
{Referrer: 'Tom', Amount: 10, Location: 'London'},
{Referrer: 'Sam', Amount: 10, Location: 'Paris'},
{Referrer: 'Henry', Amount: 10, Location: 'NY'},
{Referrer: 'Tom', Amount: 20, Location: 'London'},
{Referrer: 'Henry', Amount: 30, Location: 'NY'}
];
$scope.sum = function(name){
return $scope.data.filter(function(x) { return x.Referrer == name; })
.map(function(x) { return x.Amount; }).reduce(function(a, b) { return a + b; });
}
})
table, th, td {
border: 1px solid black;
border-collapse: collapse;
}
.totalRow{
border-style: solid;
}
.total{
text-align: right;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.7.5/angular.min.js">
</script>
<div ng-app='app' ng-controller='ctrl'>
<table>
<thead>
<tr>
<th>Referrer</th>
<th>Location</th>
<th>Amount</th>
</tr>
</thead>
<tbody>
<tr ng-init='next = $index + 1' ng-repeat-start='item in dataSorted = (data | orderBy : "Referrer")'>
<td>{{item.Referrer}}</td>
<td>{{item.Location}}</td>
<td>{{item.Amount}}</td>
</tr>
<tr class='totalRow' ng-repeat-end ng-if='!dataSorted[next] || (dataSorted[next].Referrer != item.Referrer)'>
<td colspan='2' class='total'>Total:</td>
<td>{{sum(item.Referrer)}}</td>
</tr>
</tbody>
</table>
</div>