Similar to Array.reduce, but the accumulator can returns Promise.
The array to be reduced.
A callback to be called for each value. If it returns null, the previous result will be kept.
The initial value.
The accumulated result.
Similar to Array.reduce, but the accumulator can returns Promise.
Param: values
The array to be reduced.
Param: accumulator
A callback to be called for each value. If it returns null, the previous result will be kept.
Param: init
The initial value.
Returns
The accumulated result.