In a Javascript array of objects, how can I target a specific array element by name/ID if that element is an array of objects itself?

Question

If I push objects created on the fly, including another internal array of objects, to an array, how can I add objects only to a specific object's array. Using Reviews for example:

reviews.push({ 'reviewer' : 'John', 
               'review' : 'This movie was the greatest', 
               'comments' : { 'commenter' : 'Dave',
                              'comment' : 'The review by John was too short'} 
             });

'comments' being the internal array of objects.

If at a later stage I want to add objects only to a specific object's 'comments' by it's parents name/ID, is it possible? And if so how would I go about doing it?

Using the example, If there is only 1 review with multiple comments, and the comments come at a later stage, how can I add new comments to the 'comments' array within the review object?

I am guessing I would need to have a review ID to stop duplicates etc, but that aside I'm not even sure syntactically how to do it or if it's even possible.

Thanks in advance.

comments is an object at the moment, should it be wrapped in [ .. ]? — Russ Cam
– Russ Cam, Commented Aug 16, 2013 at 9:18

Community · Accepted Answer · 2017-05-23 11:56:38Z

4

First off, comments should be an array and you have an object.

Then proceed like this:

reviews[someIndex].comments.push( { commenter: 'john', comment: 'hello!!'});

I.e.

if you need to add a comment to the first post do:

reviews[0].comments.push( { /* your comment */ } );

EDIT : I always used get() to retrieve an index but I seem to not be able to find much documentation about it, so I'm assuming (though I'm not sure) that [i] is a more standard way of doing things, hence why I changed the example. However the concept of pushing into comments doesn't change.

EDIT 2: OP wants to target a particular element in an array. I would use Array.prototype.indexOf as described here where you can find a solution for browsers that do not support indexOf as well.

edited May 23, 2017 at 11:56

CommunityBot

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answered Aug 16, 2013 at 9:20

Joe Minichino

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5 Comments

Barmar Over a year ago

Why .get(i) instead of [i]?

Aaron Over a year ago

I have to do it by the index? can I not target an object by reference? something (pseudo) like reviews.get('John').comments.push? Also 'First off, comments should be an array and you have an object' how so?

Halcyon Over a year ago

I'm guessing your get is like: Array.prototype.get = function (index) { return this[index]; };? with maybe some error checking (like out-of-bounds indexing)

Joe Minichino Over a year ago

Can't have it both ways :) Either you retain native array methods so you can use push or you set object keys for uniqueness but then there's a risk you overwrite comments by mistake without proper checks in place.

Aaron Over a year ago

This is great, but I can't target the element by a name or id, only an index?

Halcyon · Accepted Answer · 2013-08-16 09:25:55Z

0

If you want to keep track of the reviews and comments by id's I'd do something like:

var reviews = {};
review_id = "#1234";
reviews[review_id] = {
    "reviewer": "John",
    "review": "This movie was the bestest",
    "comments": {
        "#456": {
            "commenter": "HAL 9000",
            "comment": "I'm afraid I can't let you do that Dave"
        }
    }
};

Adding a comment:

reviews[review_id].comments[comment_id] = { /* .. */ };

answered Aug 16, 2013 at 9:25

Halcyon

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5 Comments

Aaron Over a year ago

This looks interesting

Joe Minichino Over a year ago

yeah it does but you give up native array utility methods like splice, push etc.

Halcyon Over a year ago

I doubt you'll need those methods, and you can make a similar implementation for objects. You probably just need a map or each function. It doesn't really matter. From a datamodeling point of view a dictionary (object) usually makes more sense than a list (array).

Aaron Over a year ago

Won't that overwrite the previous comments in 'comments' array?

Halcyon Over a year ago

I'm not sure what you mean. If you do: a = {}; a["b"] = true; a["c"] = true; you'll have two keys, b and c. You can overwrite them: a["b"] = false; and delete them: delete a["b"];

score 0 · Accepted Answer · 2013-08-16 09:46:43Z

0

for(var i=0;i<reviews.length;i++){
if(reviews[i]["reviewer"]=="John"){
   var count=Object.keys(reviews[i].comments).length/2;
   reviews[i].comments["commenter"+(count+1)]="another commenter";
   reviews[i].comments["comment"+(count+1)]="some other comment";
   console.log(count);
}
}

output

commenter "Dave"

comment "The review by John was too short"

commenter2 "another commenter"

comment2 "some other comment"

http://jsfiddle.net/gkxcj/

edited Aug 16, 2013 at 9:46

answered Aug 16, 2013 at 9:29

user2587132

1 Comment

Aaron Over a year ago

The comment needs to have a commenter (name of the person who made the comment)

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