JavaScript: Map-Like Array, Sorting and Adding -

i'm trying create map or dictionary style data structure in javascript. each string key points array of int, , i'd few simple things arrays keys point to.

i have bunch of animals, each id (1,2,3,...). want put these in map know 1,4,5 cats , 2,3,6 dogs.

here's have code explain better.

var mymap = {}; mymap["cats"] = new array(1,4,5);   //animals 1,4,5 cats mymap["dogs"] = new array(2,3,6);   //animals 2,3,6 dogs   

1) how add array? example, if animal #7 cat, following code correct?

mymap["cats"].push(7);   //so mymap["cats"] array [1,4,5,7] 

2) how sort map keys ordered number of items in arrays? in case, mymap["cats"] in front of mymap["dogs"] because array "cats" has more items array "dogs". following code correct?

mymap.sort(function(a,b){return mymap[b].length - mymap[a].length}); 

if there's more efficient way in javascript, please let me know. thank much!

seems you've answered own first question.

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as second question, you'll need array maintain sort order of map keys.

var mapkeys = object.keys(mymap);  mapkeys.sort(function(a,b){return mymap[b].length - mymap[a].length}); 

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then can iterate mapkeys obtain collections in sorted order.

mapkeys.foreach(function(key) {     console.log("processing ", key);     var indices = mymap[key]; });