AngularJS how to sum data from database in the view - mysql

Question

I have a table, with one column for each day of the week, in which with a ng-repeat, I put the hours worked on a specific project in that week.
The data gets pulled from a database.
What I'm having trouble with is, each project can have different subprojects, and when this happens, they all get put in a rowspan under the same main project, as you can see in the image ( the "SU" Project has 2 subprojects "ghfgh" and "testtesttest").
Now, the total hours in the last column gets pulled as well from the database, where all the hours of a project in a specific week are summed.
How can I make that IF a project has subprojects, their hours that week get summed in a single rowspan as well? (in the image I put an arrow showing the result wanted)
If I use the same code to give the rowspan to the subprojects, it gives the right rowspan to the total column, but obviously only shows the hours of the first subproject (in this case "ghfgh")
<tr ng-repeat="p in vm.presences">
<td ng-if="p.showProject" rowspan="{{p.projectCount}}">{{p.projectName}}</td>
<td>{{p.description}}</td>
<td>{{p.monday}}</td>
<td>{{p.tuesday}}</td>
<td>{{p.wednesday}}</td>
<td>{{p.thursday}}</td>
<td>{{p.friday}}</td>
<td>{{p.saturday}}</td>
<td>{{p.sunday}}</td>
<td ng-if="p.showProject" rowspan="{{p.projectCount}}">{{p.total}}</td>
</tr>
and the code used to check if there are multiple entries of the same project in a given week, to group them in the same rowspan is
weeklyPresences.forEach((p, i) => {
const differentProject = i === 0 || weeklyPresences[i - 1].projectName !== p.projectName;
p.showProject = differentProject;
if (differentProject) {
p.projectCount = weeklyPresences.filter(pres => pres.projectName === p.projectName).length;
} else {
p.projectCount = weeklyPresences[i - 1].projectCount;
}
});
return weeklyPresences;
any idea on how I could group the hours of the subprojects?
I was thinking about some loop that checks if a project has multiple entries like the code above, if it doesn't, the var total stays the same, otherwise, it takes them and sums them in a new var.

Answer 1

var arr= [1, 2, 3];
var sum = arr.reduce((a, b) => a + b, 0);
console.log(sum); // 6