How to remove an element from an array in js [Elements are from mongodb]

Question

The following is my array,

[
  {
    "key_id": "#K000030",
    "_id": "K000030",
    "isMaster": true,
    "specialties": [
        {
            "speciality1_count": "x039",
            "speciality1": "Infectious Disease"
        }
    ]
},
{
    "key_id": "#K000442",
    "_id": "K000442",
    "keyword": "Artificial Heart Ventricle",
    "isMaster": true,
    "specialties": [
        {
            "speciality1_count": "x011",
            "speciality1": "Cardiothoracic Surgery"
        },
        {
            "speciality2_count": "x041",
            "speciality2": "Interventional Cardiology"
        }
    ]
}

This fields are coming from mongoDb and I declared each filed in model. Here I want to delete 'isMater' and '_id' in my array.

resp.forEach(function(v,k){
    if (v) {
      delete v.isMaster;
      delete v._id;
    }
});

But its not getting deleted.I am not sure where I made a mistake. Please help.

Your code is just working fine....how did you check that it is not working? — Mamun, May 31 '18 at 05:10
You need to be careful with the "tags" you put on your question. If you tag with "javascript" then people with presume you are asking about "JavaScript", no matter what you put into the title. — Neil Lunn, May 31 '18 at 05:22
Finally,it worked beause I added .lean() to my query.Thank you all for your support. — Testimg198, May 31 '18 at 05:39

score 1 · Answer 1 · answered May 31 '18 at 05:10

Use array.map() function of JavaScript to do this.

So code will be:

array.map(function(item) {
  delete item._id;
  delete item.isMaster;
  return item;
});

Below is complete working code:

let array = [{"key_id":"#K000030","_id":"K000030","isMaster":true,"specialties":[{"speciality1_count":"x039","speciality1":"Infectious Disease"}]},{"key_id":"#K000442","_id":"K000442","keyword":"Artificial Heart Ventricle","isMaster":true,"specialties":[{"speciality1_count":"x011","speciality1":"Cardiothoracic Surgery"},{"speciality2_count":"x041","speciality2":"Interventional Cardiology"}]}];

array.map(function(item) {
  delete item._id;
  delete item.isMaster;
  return item;
});

console.log(array);

Don't use `map` if you're going to ignore the resulting mapped array - if you just want side effects use `forEach` instead (as OP is already doing). You're just mutating the original array — CertainPerformance, May 31 '18 at 05:14

score 1 · Answer 2 · answered May 31 '18 at 05:16

1

Shortest way to do this I think.

data = data.map(({_id,isMaster,...val})=>val);

var data  =[
  {
    "key_id": "#K000030",
    "_id": "K000030",
    "isMaster": true,
    "specialties": [
        {
            "speciality1_count": "x039",
            "speciality1": "Infectious Disease"
        }
    ]
},
{
    "key_id": "#K000442",
    "_id": "K000442",
    "keyword": "Artificial Heart Ventricle",
    "isMaster": true,
    "specialties": [
        {
            "speciality1_count": "x011",
            "speciality1": "Cardiothoracic Surgery"
        },
        {
            "speciality2_count": "x041",
            "speciality2": "Interventional Cardiology"
        }
    ]
}];

data = data.map(({_id,isMaster,...val})=>val);

console.log(data);

answered May 31 '18 at 05:16

Nishant Dixit

5,388
5
17
29

Hi,Nishant its not working for me. – Testimg198 May 31 '18 at 05:33
not working for me? Did you check by running above snippet? – Nishant Dixit May 31 '18 at 05:48
Its not your ode fault,i need to put .lean() in my query.Thanks. – Testimg198 May 31 '18 at 06:05

score 0 · Answer 3 · answered May 31 '18 at 05:17

Try delete the element using key delete map['keyName']; to delete from you object. Like following :

let resp = [{
    "key_id": "#K000030",
    "_id": "K000030",
    "isMaster": true,
    "specialties": [{
      "speciality1_count": "x039",
      "speciality1": "Infectious Disease"
    }]
  },
  {
    "key_id": "#K000442",
    "_id": "K000442",
    "keyword": "Artificial Heart Ventricle",
    "isMaster": true,
    "specialties": [{
        "speciality1_count": "x011",
        "speciality1": "Cardiothoracic Surgery"
      },
      {
        "speciality2_count": "x041",
        "speciality2": "Interventional Cardiology"
      }
    ]
  }
];

resp.forEach(function(v,k){
   if(v){
      delete v['isMaster'];
      delete v['_id'];
   }
});

console.log(resp)

Note: In some JavaScript engine, the delete keyword might hurt performance as it will undo compile / JIT optimization.

How to remove an element from an array in js [Elements are from mongodb]

3 Answers3