Javascript: Removing an object from array by checking it's attribute

Question

I might have written a pretty confusing title but my question is rather simple.

I'm looking for an efficient way to remove an item from an array. But my array is full objects that has been stringified (I'm writing my app on Node.js and I'm using JSON.stringify method). So my array is like this;

"{\"userID\":\"15\",
  \"possibleFollowers\":[
      {\"followerID\":\"201\",\"friends\":716},
      {\"followerID\":\"202\",\"friends\":11887},
      {\"followerID\":\"203\",\"friends\":11887}],
  \"name\":\"John\",
  \"lon\":\"Doe\"}"

My question is on Javascript(or Node). If I wanted to remove the from possibleFollowers with "followerID: 202", how would I be able to do that efficiently?

do you want to remove from JSON string or Javascript object ? — Diode
– Diode, Commented Oct 19, 2012 at 7:49
@Diode the object from the possible folllowers. I mean if it is "possibleFollowers\":[ {\"followerID\":\"201\",\"friends\":716}, {\"followerID\":\"202\",\"friends\":11887}, {\"followerID\":\"203\",\"friends\":11887}], after the removal it should look like this; — Ali
– Ali, Commented Oct 19, 2012 at 7:51
"possibleFollowers\":[ {\"followerID\":\"201\",\"friends\":716}, {\"followerID\":\"202\",\"friends\":11887} ] — Ali
– Ali, Commented Oct 19, 2012 at 7:51

Bergi · Accepted Answer · 2012-10-19 07:56:39Z

3

var string = "…";

var obj = JSON.parse(string);
obj.possibleFollowers = obj.possibleFollowers.filter(function(fol) {
    return fol.followerID != "202";
});
string = JSON.stringify(obj);

answered Oct 19, 2012 at 7:56

Bergi

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1 Comment

Ja͢ck Over a year ago

Beware of IE support though; IE >= 9 .. for node.js it shouldn't matter i guess :)

Diode · Accepted Answer · 2012-10-19 07:54:33Z

2

var data = "{\"userID\":\"15\",\"possibleFollowers\":[{\"followerID\":\"201\",\"friends\":716},{\"followerID\":\"202\",\"friends\":11887},{\"followerID\":\"203\",\"friends\":11887}],\"name\":\"John\",\"lon\":\"Doe\"}";

var dataObject = JSON.parse(data);
dataObject.possibleFollowers = dataObject.possibleFollowers.filter(function(follower) {
    return !(follower.followerID == "202");
});
data = JSON.stringify(dataObject);

answered Oct 19, 2012 at 7:54

Diode

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2 Comments

Ali Over a year ago

Thank you so much for the answer. I haven't tried yet but looks just fine. However I was wondering, does your method and the well suggest splice method have a huge difference in terms of efficiency?

Michelle Tilley Over a year ago

I was going to comment on the dangers of modifying an array while looping over it by index, and then the answer changed to use filter, which is what I was going to suggest! +1

Peter · Accepted Answer · 2012-10-19 07:55:59Z

0

In javascript, the splice method is used to delete an array element by index.

see :

http://www.roseindia.net/java/javascript-array/javascript-array-remove-index.shtml

edited Oct 19, 2012 at 7:55

answered Oct 19, 2012 at 7:50

Peter

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2 Comments

Ali Over a year ago

Seen, searched but could not adopt to my problem. Yet thanks for the suggestion.

Ali Over a year ago

An additionally I would like to search for the object, then delete it.

Alexey Sidorov · Accepted Answer · 2012-10-19 07:47:13Z

-1

try just to delete it by using "delete"

for (var i in possibleFollowers) {
    if (possibleFollowers[i]['followerId'] == '216') {
        delete possibleFollowers[i];
    }
}

answered Oct 19, 2012 at 7:47

Alexey Sidorov

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1 Comment

Ja͢ck Over a year ago

That will create a null entry in its place.

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