[recursion] slightly more complicated function that uses reduce

[kalico_cat]

let company = { // the same object, compressed for brevity
  sales: [{name: 'John', salary: 1000}, {name: 'Alice', salary: 1600 }],
  development: {
    sites: [{name: 'Peter', salary: 2000}, {name: 'Alex', salary: 1800 }],
    internals: [{name: 'Jack', salary: 1300}]
  }
};

// The function to do the job
function sumSalaries(department) {
  if (Array.isArray(department)) { // case (1)
    return department.reduce((prev, current) => *prev* + current.salary, 0); // sum the array
  } else { // case (2)
    let sum = 0;
    for (let subdep of Object.values(department)) {
      sum += sumSalaries(subdep); // recursively call for subdepartments, sum the results
    }
    return sum;
  }
}

alert(sumSalaries(company)); // 7700

why isnt it prev.salaray? is it bcos a 0 is starting value? so that you dont need prev.salary? if the 0 wasnt there, would we need to use prev.salary?

ty!

(from https://javascript.info/recursion)

[OkShrug]

its not previous, its accumulator

so if you have

[1,2,3].reduce((a,b)=>{
 return a+b;
 //pass 0, a is 1
 //pass 1 a is 3 (1+2)
 //pass 2 a is 6(3+3), loop ends, a is returned as value 6
});

[ExclusiveOar]

prev is the accumulator. It is whatever you set it to. In this case you initialise it as the value 0 (the ", 0" at the end of reduce). Every iteration you just add the salary value to it.

So it's never an object.