树递归：如何获取所选树节点的父根

Question

I have a tree-like structure of a json object

{
  "saxena": {
    "chewning": {
      "betten": {},
      "ching": {},
      "kelley": {}
    },
    "kobrinsky": {
      "karniely": {},
      "naveh": {},
      "rozenfeld": {},
      "shalom": {}
    },
    "schriever": {
      "brinker": {},
      "mcleland": {},
      "merrick": {}
    },
    "vacant": {
      "akers": {},
      "carlton": {
        "marvin": {}
      },
      "fox": {
        "glover": {
          "clements": {},
          "koya": {}
        },
        "holden": {}
      }
    }
  },
  "bill": {
    "phil": {
      "bob": {},
      "smith": {},
      "hello": {}
    },
    "bye": {
      "ok": {},
      "hmm": {},
      "no": {},
      "alright": {}
    }
  }
}

The root names are saxena and bill. I would like to create a function that can determine the root name of who the user searches for.

For the most simplest case, if they search for saxena, it returns saxena. If they return bill, it returns bill.

For a more complex case, saxena will be returned if the user searches for any of the names under her.

For example, if I search for betten, akers, glovers, or koya, saxena will be returned.

And if I search for bob, smith, or alright, bill will be returned.

This is my work so far. I tried using recursion, but for some reason when I find the selected name, I return an undefined.

var findRootName = function(data, ltmName) {
    for (var key in data) {
        if (key == ltmName) {
            return key;
        } else {
            findNode(data[key], ltmName);
        }
    }
}

var findNode = function(data, ltmName) {
    for (var key in data) {
        if (key == ltmName) {
            return key;
        } else {
            findNode(data[key], ltmName);
        }
    }
}

http://jsfiddle.net/gthnfta7/7/

Can somebody help me and figure out why my recursive function isn't working?

Answer 1

An alternative technique, if you need to make many calls over the same data, is something like the following:

function makeSearcher(data) {
    var paths = (function makePaths(data, parentPath, store) {
        var path = parentPath || [];
        results = store || {};
        Object.keys(data).forEach(function(key) {
            var newPaths = path.concat(key);
            results[key] = newPaths;
            makePaths(data[key], newPaths, results);
        });
        return results;
    })(data);
    return function(key) {
        var path = paths[key];
        return path && path[0];
    };
}

var search = makeSearcher(data);

search('clements'); //=> 'savena'

Note that the internal makePaths function is broader than the use here, as it could also be use to return a result like

[ "saxena", "vacant", "fox", "glover", "clements" ]

Answer 2

The problem is that you're not returning anything in the event that the node is found. You can simplify your function by writing it like this:

var findParent = function(data, childName) {
  for (var key in data) {
      if (key === childName || findParent(data[key], childName)) {
        return key;
      }
  }
};