javascript - Better Solution for Unflattening Array of Objects -

for following array of objects

[  {"corp": "abc", "t1": "hw a/v", "t2": "a/v system","t3": "audio","prod": "audio system","mfr": "one"},  {"corp": "abc", "t1": "hw a/v", "t2": "a/v system","t3": "audio","prod": "audio system","mfr": "two"},  {"corp": "abc", "t1": "hw a/v", "t2": "a/v system","t3": "video","prod": "video system","mfr": "other"} ] 

i intend unflatten object 1 below :

[{ "corp": "abc", "list": [{     "t1": "hw a/v",     "list": [{         "t2": "a/v system",         "list": [{             "t3": "audio",             "list": [{                 "prod": "audio system",                 "list": [                     {"mfr": "one"},                     {"mfr": "two"}                 ]             }]         },         {             "t3": "video",             "list": [{                 "prod": "video system",                 "list": [                     {"mfr": "other"}                 ]             }]         }]     }] }] 

}] did result intend described above. used underscore result. following code snippet did job me :

var items = _.map(_.groupby(itemlist, 'corp'), function (a) {         return _.extend(_.pick(a[0], 'corp'), {             list: _.map(_.groupby(a, 't1'), function (b) {                 return _.extend(_.pick(b[0], 't1'), {                     list: _.map(_.groupby(b, 't2'), function (c) {                         return _.extend(_.pick(c[0], 't2'), {                             list: _.map(_.groupby(c, 't3'), function (d) {                                 return _.extend(_.pick(d[0], 't3'), {                                     list: _.map(_.groupby(d, 'prod'), function (e) {                                         return _.extend(_.pick(e[0], 'prod'), {                                             list: _.map(e, function (elem) {                                                 return _.pick(elem, 'mfr')                                             })                                         });                                     })                                 });                             })                         });                     })                 });             })         });     }); 

now, looking for, if can enhance solution. want optimize both space , time process.

ps: in morning, had asked similar question requesting solution, , question marked as too broad , put on hold, so have added solution question, looking better solution.

thanks

in order avoid imbricated statements, may want define list of 'expand keys' , iterate on them.

it's half-tempting automatically extract keys like:

expandkeys = _.keys(itemlist[0]); 

but since javascript doesn't guarantee order of keys in object, should define list explicitly instead.

below example code.

var itemlist = [    {"corp": "abc", "t1": "hw a/v", "t2": "a/v system", "t3": "audio", "prod": "audio system", "mfr": "one"},    {"corp": "abc", "t1": "hw a/v", "t2": "a/v system", "t3": "audio", "prod": "audio system", "mfr": "two"},    {"corp": "abc", "t1": "hw a/v", "t2": "a/v system", "t3": "video", "prod": "video system", "mfr": "other"}  ];    var expandkeys = [ 'corp', 't1', 't2', 't3', 'prod', 'mfr' ];    function expandlist(list, keys) {    var node, obj, root = {};      _.each(list, function(item) {      obj = root;      _.each(keys, function(key) {        obj = (obj.list = obj.list || []);        node = _.find(obj, function(i) { return i[key] == item[key]; });          if(node === undefined) {          obj.push(node = {});          node[key] = item[key];        }        obj = node;      });    });    return root.list;  }    var res = expandlist(itemlist, expandkeys);  console.log(res);

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