Whitelist nested properties using this particular object format

Question

need "whitelist" object to look like this:

{
    a: {
        b: {
            c: ''
        }
    }
}

apply to:

{
    a: {
        b: {
            c: 1
        }
        d: 2
        e: 3
    }
}

result:

{
    a: {
        b: {
            c: 1
        }
    }
}

Any suggestions? Not sure how to implement this using underscore. Was looking at _.pick but ran into trouble with the nesting.

Answer 1

Recursion with Array.prototype.reduce():

function getPaths(obj, whiteList) {  
  return Object.keys(whiteList)
    .reduce(function(whiteObj, key) {
      if (!obj.hasOwnProperty(key)) {
      } else if(typeof obj[key] === 'object') {
        whiteObj[key] = getPaths(obj[key], whiteList[key]);
      } else {
        whiteObj[key] = obj[key];
      }
    
      return whiteObj;
    }, {})
}

var whiteList = {
  a: {
    b: {
      c: ''
    }
  },
  g: ''
};

var obj = {
  a: {
    b: {
      c: 1
    },
    d: 2,
    e: 3
  }
};

var result = getPaths(obj, whiteList);

console.log(result);