Function sumBy

sumBy<T>(items: readonly T[], select: (item: T) => number): number
Sums a list of items by projecting each to a number.
Type Parameters
- T
Parameters
- items: readonly T[]
  The items to reduce.
- select: (item: T) => number
  Maps each item to the number to add.
Returns number
The total. Returns 0 for an empty list.
Example
```
sumBy(rows, (r) => r.revenue);
```
- Defined in math/index.ts:119