Find property by name in a deep object

Question

I have a HUGE collection and I am looking for a property by key someplace inside the collection. What is a reliable way to get a list of references or full paths to all objects containing that key/index? I use jQuery and lodash if it helps and you can forget about infinite pointer recursion, this is a pure JSON response.

fn({ 'a': 1, 'b': 2, 'c': {'d':{'e':7}}}, "d");  // [o.c]  fn({ 'a': 1, 'b': 2, 'c': {'d':{'e':7}}}, "e"); // [o.c.d]  fn({ 'aa': 1, 'bb': 2, 'cc': {'d':{'x':9}}, dd:{'d':{'y':9}}}, 'd'); // [o.cc,o.cc.dd] 

fwiw lodash has a _.find function that will find nested objects that are two nests deep, but it seems to fail after that. (e.g. http://codepen.io/anon/pen/bnqyh)

Answer 1

This should do it:

function fn(obj, key) {     if (_.has(obj, key)) // or just (key in obj)         return [obj];     // elegant:     return _.flatten(_.map(obj, function(v) {         return typeof v == "object" ? fn(v, key) : [];     }), true);      // or efficient:     var res = [];     _.forEach(obj, function(v) {         if (typeof v == "object" && (v = fn(v, key)).length)             res.push.apply(res, v);     });     return res; } 

Answer 2

a pure JavaScript solution would look like the following:

function findNested(obj, key, memo) {   var i,       proto = Object.prototype,       ts = proto.toString,       hasOwn = proto.hasOwnProperty.bind(obj);    if ('[object Array]' !== ts.call(memo)) memo = [];    for (i in obj) {     if (hasOwn(i)) {       if (i === key) {         memo.push(obj[i]);       } else if ('[object Array]' === ts.call(obj[i]) || '[object Object]' === ts.call(obj[i])) {         findNested(obj[i], key, memo);       }     }   }    return memo; } 

here's how you'd use this function:

findNested({'aa': 1, 'bb': 2, 'cc': {'d':{'x':9}}, dd:{'d':{'y':9}}}, 'd'); 

and the result would be:

[{x: 9}, {y: 9}]