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

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
– Mamun, Commented May 31, 2018 at 5:10
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
– Neil Lunn, Commented May 31, 2018 at 5:22
Finally,it worked beause I added .lean() to my query.Thank you all for your support. — Testimg198
– Testimg198, Commented May 31, 2018 at 5:39

Vikasdeep Singh · Accepted Answer · 2018-05-31 05:10:58Z

1

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);

answered May 31, 2018 at 5:10

Vikasdeep Singh

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2 Comments

CertainPerformance Over a year ago

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

Testimg198 Over a year ago

@ViJordan,I dont know why but its not working.

Nishant Dixit · Accepted Answer · 2018-05-31 05:16:18Z

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, 2018 at 5:16

Nishant Dixit

5,5125 gold badges22 silver badges32 bronze badges

3 Comments

Testimg198 Over a year ago

Hi,Nishant its not working for me.

Nishant Dixit Over a year ago

not working for me? Did you check by running above snippet?

Testimg198 Over a year ago

Its not your ode fault,i need to put .lean() in my query.Thanks.

Sudhir Ojha · Accepted Answer · 2018-05-31 05:17:52Z

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.

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