How do I deeply traverse a JSON-like data structure to return a total of something

Question

I apologize for the vague question. Hopefully my example adds some clarity to my question... So I have a hierarchical data structure like this:

var Company = {
    root: {
        title: 'CEO',
        employees: [{
            title: 'Vice President',
            employees: [{
                title: 'Sales Lead'
            }, {
                title: 'Marketing Lead'
            }]
        }]
    }
};

My question is how would I find out the total number of employees in the root object? Visually, one can see that there are 3 employees in the company. I am working with recursion to try and solve this problem, but I just can't seem to get it working right... or working at all for that matter. I appreciate any help, tips, or advice :)

Answer 1

You can use .reduce with a named function that can be called recursively. The base case would be if an object has no employees.

const totalEmployees = Company.root.employees.reduce(countEmployees, 0);

function countEmployees(prev, next) {
    // count *this* employee
    let sum = prev + 1;
    if (next.employees && next.employees.length) {
      // count any nested employees
      sum += next.employees.reduce(countEmployees, 0);
    }
    return sum;
}

Answer 2

You can use a recursive function to loop though a nested object structure.

Here is how you do it.

function countEmployee(root){

    if(!root.employees){
        return 0;
    }

    var numOfEmployee = root.employees.length;; 

    var count = 0;

    for(var i=0; i<numOfEmployee; i++){
        count = count + countEmployee(root.employees[i]);
    }

    numOfEmployee = numOfEmployee + count;

    return numOfEmployee;
}

countEmployee(Company.root); //return 3