CODEWITHSUNDEEP
javascriptunderscore.js
WelcomeTo
WelcomeTo

Reputation: 20581

Underscore.js Find and return element in nested array

I have data-structure like this: 

[
    {
        "name": "AAAA",
        "children": [
            {"name": "vvv", "id": 3},
            {"name": "vvv22", "id": 4}
        ]
    },
    {
        "name": "BBBB",
        "children": [
            {"name": "ggg", "id": 5},
            {"name": "ggggv22", "id": 6}
        ]
    },
]

And I want to find and return child with given ID. How to achieve this using Underscore.js?

My current realisation without using Underscore:

for (var i = 0; i < data.length; i++) {
     var dataItem= data[i];
     for (var j = 0; j < dataItem.children.length; j++) {
        var child = dataItem.children[j];
        if (child .id == id) {
             return child;  
        }
     }
}

Upvotes: 7

Views: 9736

Answers (2)

nikoshr
nikoshr

Reputation: 33344

  1. Pluck the children keys from your top level objects
  2. Flatten the resulting array
  3. Find the first object matching the condition, e.g having the correct id
  4. Chain these operations

which leads to

var res = _(data).chain().
    pluck('children').
    flatten().
    findWhere({id: 3}).
    value();

And a demo

var data = [
    {
        "name": "AAAA",
        "children": [
            {"name": "vvv", "id": 3},
            {"name": "vvv22", "id": 4}
        ]
    },
    {
        "name": "BBBB",
        "children": [
            {"name": "ggg", "id": 5},
            {"name": "ggggv22", "id": 6}
        ]
    }
];
var res = _(data).chain().
    pluck('children').
    flatten().
    findWhere({id: 3}).
    value();
    
console.log(res);
<script src="http://underscorejs.org/underscore-min.js"></script>

Upvotes: 21

Mritunjay
Mritunjay

Reputation: 25882

I got this function using underscore which will do your work.

var getChild = function(id,data){
    var allChildren = _.flatten(_.pluck(data,'children'));
    var childWithId = _.find(allChildren,function(child){return child.id == id});
    return childWithId;
}

var child = getChild(5,data);
console.log(child);

Upvotes: 4

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