You can use the Spread Operator to accomplish that.

This code snippet has a function called addElements which find the target and adds the new elements to the children array.

var obj = {
  "name": "Root",
  "children": [{
      "name": "child1"
    },
    {
      "name": "child2"
    }
  ]
};


var newArray = [
   { "name": "child11"}, 
   { "name": "child12"}
];

var addElements = function(target, array) {
  obj.children.forEach(function(child) {
    if (child.name === target) {
      child['children'] = [...(child['children'] || []), ...newArray];
      return;
    }
  });
};

addElements('child1', newArray);


console.log(obj);

See? now your obj.childre[0].children array contains the new elements.

I would do below if I imagine well your typo:

const foo = { a: 'vala', b: 'valb', childval : { x : 'valx' } };
const bar = { c: 'valc' };

foo.childval = { ...foo.childval, ...bar };

spread syntax is neat for these situations

See this fiddle: http://jsfiddle.net/2Dvws/

It will find an object by ID. And push the new child. Since every object within Javascript is a reference, you can return it as an var.

var ob = {
    name: "root",
    id: 1,
    children: [
        {
        name: "child one",
        id: 11,
        children: [
            {
            name: "grand child 1",
            id: 111,
            children: []},
        {
            name: "grand child 2",
            id: 112,
            children: []}
        ]},
    {
        name: "child two",
        id: 12,
        children: []}
    ]
};

The function which will return the found element. Will look into all child elements.

function findObjectById(root, id) {
    if (root.children) {
        for (var k in root.children) {
            if (root.children[k].id == id) {
                return root.children[k];
            }
            else if (root.children.length) {
                return findObjectById(root.children[k], id);
            }
        }
    }
};

var bla = findObjectById(ob, 111);

console.log(bla);
bla.children.push({
        name: "child x",
        id: 1111,
        children: []
});
console.log(ob);

Output is that child with id 111 will have 1 child with id 1111 ​

JSON stands for JavaScript Object Notation. A JSON object is really a string that has yet to be turned into the object it represents.

To add a property to an existing object in JS you could do the following.

object["property"] = value;

or

object.property = value;

If you provide some extra info like exactly what you need to do in context you might get a more tailored answer.

What i basically understood about what you wanna to do is this:

var obj = {
    children:[]
}
obj.children.push({test:'Hello world'});
console.log(obj.children);//[Object { test="Hello world"}]

Am i right?

You have nested arrays, so you need to access the elements in the arrays by their index.

Copyvar hold = body.rows[0].elements[0].duration_in_traffic.text;

The value you're looking for, is in the objects array in the JSON, but it's in an object which is the first in an array:

var jsonVar = {"meta": {"limit": 20, "next": null, "offset": 0, "previous": null, "total_count": 1}, "objects": [{"id": 2, "nom": "", "resource_uri": "/api/v1/client/2/", "telefon": "", "user": {"date_joined": "2013-05-15T12:28:40", "first_name": "", "id": 51, "is_active": true, "is_staff": false, "last_login": "2013-05-16T06:20:43", "last_name": "", "resource_uri": "/api/v1/user/51/", "username": "gli"}}]}

alert(jsonVar.objects[0].resource_uri);

See here:

http://jsfiddle.net/SpAm/tnWmL/

I finally managed to do it with the JSON that i got from the server, it had to be parsed with JSON.parse and then sent to this method buildTree() that the material team gives us

ngOnInit(){
const dataObject = JSON.parse(jsonMessage);
const data = this.buildFileTree(dataObject, 0);
}

buildFileTree(obj: { [key: string]: any }, level: number): FileNode[] {
    return Object.keys(obj).reduce<FileNode[]>((accumulator, key) => {
      const value = obj[key];
      const node = new FileNode();
      node.name = key;
      if (value != null) {
        if (typeof value === 'object') {
          node.children = this.buildFileTree(value, level + 1);
        } else {
          node.type = value;
        }
      }
      return accumulator.concat(node);
    }, []);
  }

try this

$.each(resp.message, function(index, dogs) {
    var subdog = dogs.length;
    console.log(subdog);        
});

In your JSON tests is not an array but an object, and you cannot push to an object. So this line is wrong:

ctrl.otsact.tests.push({});

You have to change it to:

ctrl.otsact.tests[MYNEWID] = MYNEWOBJECT;