How to add child nodes in a json object using javascript?

Question

I am building a JSON file dynamically. I want to add a JSON array in the JSON object. The JSON looks like-

{"name":"Root",
  "children":[
   {"name":"child1"},
   {"name":"child2"}
  ]}

Now, I want to add -

[{"name":"child11"},{"name":"child12"}]

under "child1" object. How to do it? I have also tried keeping blank children object while creating the original JSON object, but JSON parser doesn't keep those empty children block. In current scenario, when I am using push() function to add new child it throws exception. Any help is much appreciated. Thanks in advance!!

Edit1: I think I didn't made myself clear enough. I have researched SO before posting this question, and I guess this is not a duplicate question. My target JSON is -

{
  "name": "Root",
  "children": [{
      "name": "child1",
	  "children": [{
		{"name": "child11"},
		{"name": "child12"}
	  }]
    },
    {
      "name": "child2",
	  "children": [{
		{"name": "child21"},
		{"name": "child22"}
	  }]
    }
  ]
};

Here is the code snippet that I am trying to run -

flare = {
  "name": "Root",
  "children": [{
      "name": "child1",
	  "children": [{
		{"name": "child11"},
		{"name": "child12"}
	  }]
    },
    {
      "name": "child2",
	  "children": [{
		{"name": "child21"},
		{"name": "child22"}
	  }]
    }
  ]
};
var updatedJson = twoLevelSelection(flare);
function twoLevelSelection(json){
	var root = flare.name;
	var string_json = '';
	string_json = '{"name": "'+root+'","children": [';
	flare.children.forEach(
	function(d){
		string_json = string_json+ '{"name":"'+d.name+'","children":[]},';
	}
	);
	string_json = string_json.substring(0,string_json.length-1);
	string_json = string_json + ']}';
	return JSON.parse(string_json);
}
// data is the original data.i.e - flare
// d is the clicked node, under which children to be added
function traverse(data,d){
var queue = [];
var next = data;
while(next){
	if(next.children){
		next.children.forEach(
		function(k){
			queue.push(k);
		}
		)
	}
	if(queue[0].name==d.name){
		alert(queue[0].children);
		//d.children = queue[0].children;
		var child_string='';
		var child_array = [];
		queue[0].children.forEach(
		function(j){
			child_string = '{"name": "'+j.name+'"}';
			child_array.push(child_string);
		}
		);
		console.log(child_array);
		d.children = [...child_array];
		console.log(updatedJson);
		//update(updatedJson);
		break;
	}else{
		next= queue.shift();
	}
}
}

The traverse() will be called on a click event. Sorry, for not providing clarity at first place. Thanks!

Welcome to SO. Please visit the help center to see what and How to Ask. HINT: Post effort and code — mplungjan
– mplungjan, Commented Jan 29, 2018 at 13:39
the question was already closed i cannot find it anymore - this was some days ago — messerbill
– messerbill, Commented Jan 29, 2018 at 13:39

Ele · Accepted Answer · 2018-01-30 10:09:38Z

2

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.

edited Jan 30, 2018 at 10:09

answered Jan 29, 2018 at 13:48

Ele

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3 Comments

Kaustav Roy Over a year ago

Thank you for the response. I wasn't clear about my query. Actually, I want to add new children under "child1" not under "root". Please find the edit and the code above.

Kaustav Roy Over a year ago

Thank you @ele. Actually I took a different approach to achieve the goal. Your solution works great. Thanks!

Ele Over a year ago

@KaustavRoy great. An accepted answer would be nice :-)

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