How to use recursion to update a locally scoped variable

Forgive me if this is too much of a general question but I seem to run into this problem frequently when I need to develop recursive algorithms which update some value on each recursive call. Please take this example bellow:

I want to make a recursive algorithm that accumulates the ages of the given profile and all the kids and kids of kids etc that exist within that profile.

Profile structure:

const profile = {    name: 'peter',    age: 56,    kids: [{      name: 'jill',      age: 23,      kids: [{        name: 'jeter',        age: 1      }, {        name: 'bill',        age: 2      }]    }]  }  

If I declare a variable outside of the scope of the function and update that it works. Like so:

let totalage = 0  function getAge(profile) {    totalage = profile.age + totalage    if(!profile.kids) return    for(const kid of profile.kids) {      getAge(kid)    }  }  getAge( profile)  console.log(totalage)  

By this logic, to make the function more reusable I want to make a shell function that sets up the age variable so it doesnt have to be globally declared any time I want to get all the ages, but this solution returns 0, the original age value:

function getAges(profile) {    let age = 0    recurs( profile, age)    return age  }    function recurs(profile, age) {    age = profile.age + age    if(!profile.kids) return    for(const kid of profile.kids) {      recurs(kid, age)    }  }  console.log(getAges(profile))  

Any idea what is wrong?

Again, please forgive me if this is a newbie question I'm just trying to learn and improve. Thanks

https://stackoverflow.com/questions/67029881/how-to-use-recursion-to-update-a-locally-scoped-variable April 10, 2021 at 08:59AM