Adding decimal numbers instead of concatenating

I am trying to sum multiple decimals numbers together however when I console the result it is showing a concatenated result with an undefined in front of it

  for (let i = 0; i < this.performInternationalSwiftPaymentsService.bopSplit.length; i++) {
    this.totalZARForeign += this.performInternationalSwiftPaymentsService.bopSplit[i].randValue;
  }
  console.log(this.totalZARForeign)

console result –> undefined4752.861188.22

The result I want is for it to add 4752.86 and 1188.22 together in this example

Any idea what I am doing wrong. I also tried adding a parseFloat here this.totalZARForeign += parseFloat(this.performInternationalSwiftPaymentsService.bopSplit[i].randValue); but then I get NaN in the console result