ng2-pipes/src/app/pipes/math/sum.ts

Useful angular2 pipes

import {PipeTransform, Pipe, Injectable} from '@angular/core';

@Injectable()
@Pipe({name: 'sum'})
export class SumPipe implements PipeTransform {

  transform(arr: number[]):number|number[] {
    return !Array.isArray(arr)
      ? arr
      : arr.reduce((sum, curr) => sum + curr, 0);
  }
}