How to recursively objectify a string-CodePudding

While trying to become more comfortable with recursive functions, I attempted to write a function that takes a dot-separated string and converts that into an object. So, given the following string: user.first.name.robert this function should return the following object:

{
  user: {
    first: {
      name: 'robert'
    }
  }
}

Here's my attempt:

function objectifyHelper(array, object) {
    if (array.length === 2) {
        const [key, value] = array;
        object[key] = value;
        return object;
    } else {
        object[array[0]] = objectifyHelper(array.slice(1), object); 
        return object;
    }
}

function objectify(string) {
    const tokens = string.split('.');
    return objectifyHelper(tokens, {});
}

const str = 'user.first.name.robert';
const result = objectify(str);

This gets me the following result:

result <ref *1> {
  name: 'robert',
  first: [Circular * 1],
  user: [Circular * 1]
}

What am I doing wrong?

CodePudding user response：

You're only ever creating a single object here:

return objectifyHelper(tokens, {});

that then gets used every time a property is assigned to it. You need to instead create a new object when recursing, and not only inside of objectify.

A simpler approach would be:

const objectify = string => string
  .split('.')
  .reduceRight(
    (innerObj, prop) => ({ [prop]: innerObj })
  );

const str = 'user.first.name.robert';
const result = objectify(str);
console.log(result);

CodePudding user response：

You are almost there. However, if your helper accepts an object but also returns it, be consistent in your recursive call

function objectifyHelper(array, object) {
    if (array.length === 2) {
        const [key, value] = array;
        object[key] = value;
        return object;
    } else {
        object[array[0]] = objectifyHelper(array.slice(1), {}); 
        return object;
    }
}

function objectify(string) {
    const tokens = string.split('.');
    return objectifyHelper(tokens, {});
}

const str = 'user.first.name.robert';
const result = objectify(str);

console.log(result)

Note that this only changes your

object[array[0]] = objectifyHelper(array.slice(1), object);

object[array[0]] = objectifyHelper(array.slice(1), {});