How to find sum using reduce, pipe and combinelatest?

Question

Values is list of obervables over input fields

    var example = combineLatest(values);

How do I find sum of values in text field.

    example.subscribe(val => {
        console.log('Sum:', val);
    });

Having subscriber over it gives me output of the form

Sum: (2) ["1", "2"]

Piping over combineLatest gives me NaN

     .pipe(reduce((acc, one) => {
         var a =Number(acc) + Number(one);
         console.log(a);
         return a;
     }, 0));

As mentioned in your previous question reduce only emits if your Observable completes. To be able to analyse your issue we need to know what exactly your Observable (values) is and when those are set and how you complete them. — Jonathan Stellwag, Mar 06 '20 at 18:43

score 3 · Accepted Answer · answered Mar 06 '20 at 19:00

3

You don't have to reduce the Observable, you have to reduce the array it emits.

var example = combineLatest(values).pipe(
  map(array => array.reduce((pv, cv) => pv + Number(cv), 0))
);

answered Mar 06 '20 at 19:00

frido

1 Answers1