sumBy<N extends num> method
N
sumBy<N extends num>(
- N mapper(
- T element
The sum of the values returned by the mapper
function.
Examples:
expect([1, 2, 3, 4, 5].sumBy((e) => e), 15);
expect([1.5, 2.5, 3.3, 4, 5].sumBy((e) => e), 16.3);
expect(['a', 'ab', 'abc', 'abcd', 'abcde'].sumBy((e) => e.length), 15);
Implementation
N sumBy<N extends num>(N Function(T element) mapper) {
N result = 0 as N;
for (var value in this) {
result = result + mapper(value) as N;
}
return result;
}