如果在 reduce() 中检查总和 function

Question

I am trying to iterate through an array in typescript, but on occasion, inside the array there will be an empty value or NaN (null) value by default. this really mucks up my sum function, as it is trying to call parseInt() on a null value, so the function also returns NaN. How can I make an if condition inside of this function to check for Number() first otherwise skip/continue? I know I can naively have a for each loop, and check for this inside of an if statement, but that is not ideal.

    sumOwnershipLiabilityPercentages(): number{
        // return the sum of all the percentage ownerships
        return this.liabilitiesOwnershipList.reduce((prev: number, cur: any) => prev + parseInt(cur.percentage), 0);
    }

Answer 1

You can make the summation conditional.

const sum = d.reduce((p: number, c: number) => p += (c) ? c : 0)

if you want to make a more elaborate if statements do it like so

const sum2 = d.reduce((p: number, c: number) => {
   if (c)
      return p += c;
   else
      return p += 0;
   })

or, in your case, something like this

return this.liabilitiesOwnershipList.reduce((prev: number, cur: any) => {
    if (cur && cur?.percentage)
      return prev += parseInt(cur.percentage);
    else
      return prev += 0;
  });