How to remove specific column from data array (JS)

Question

I have a list

let list = [ 
{ 
  id: "247", 
  order_number: "21251", 
  tel: 13911111, 
  weight: "10kg" 
}, 
{ 
  id: "245", 
  order_number: "223", 
  tel: 31, 
  weight: "10kg" 
},
{ 
  id: "123", 
  order_number: "312312321", 
  tel: 3213123, 
  weight: "10kg" 
}
];

Now I only wan to remove the specific column, such as 'tel', to get a new list. Is there any elegant way to do it? or I have to loop the whole data to use splice method?

findIndex followed by splice, surely that's straightforward enough? — CertainPerformance
– CertainPerformance, Commented Jun 12, 2018 at 2:29
Possible duplicate of How to remove properties from an object array?, though you should pick the highest voted answer, not the accepted one, or the comment underneath it — in your case: list.map(({id, order_number, weight}) => ({id, order_number, weight})). — Sebastian Simon
– Sebastian Simon, Commented Jun 12, 2018 at 2:38

Christopher Francisco · Accepted Answer · 2018-06-12 02:42:50Z

12

I would argue against using delete keyword because you would be mutating the list instead of making a new one, and also because of its behavior explained in the documentation, Specially those lines about:

Any property declared with let or const cannot be deleted from the scope within which they were defined
If a property with the same name exists on the object's prototype chain, then, after deletion, the object will use the property from the prototype chain (in other words, delete only has an effect on own properties).
Any property declared with var cannot be deleted from the global scope or from a function's scope.

Instead you can map().

listWithoutTel = list.map(({ tel, ...item }) => item);

Here you'd be using the rest parameters to put all properties but the unwanted one (in this case tel) of a destructured object in a variable named item and return in immediately.

answered Jun 12, 2018 at 2:42

Christopher Francisco

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5 Comments

Ian Over a year ago

if the property is like 'tel num' , how to handle it? @Christopher Francisco

Tim Harker Over a year ago

Best answer I've seen. Cheers!

wingman Over a year ago

How could you make "tel" a variable?

Zubair Ahmd Over a year ago

@Ian I understand its pretty old post but did you get solution to your comment?

Zubair Ahmd Over a year ago

@Ian using developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… link from anwer post Its possible to pass feild name with space like listWithoutTel = list.map(({ 'tel num':telnum, ...item }) => item);

Sebastian Simon · Accepted Answer · 2018-06-12 02:52:05Z

2

In static way:

let list = [
  {
    id: "27",
    order_number: "21251",
    tel: 13911111,
    weight: "10kg"
  },
  {
    id: "245",
    order_number: "223",
    tel: 31,
    weight: "10kg"
  },
  {
    id: "123",
    order_number: "312312321",
    tel: 3213123,
    weight: "10kg"
  }
];
let new_list = list.map(function(obj) {
  return {
    id: obj.id,
    order_number: obj.order_number,
    weight: obj.weight
  }
});

console.log(list);
console.log(new_list)

This way, you keep both your old array and new array.

If you want to do it in dynamic way, you may use forEach to check the keys.

edited Jun 12, 2018 at 2:52

Sebastian Simon

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answered Jun 12, 2018 at 2:44

tung yu

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1 Comment

NoBullMan Over a year ago

Can this be made dynamic? User can select what columns to be removed (tel or tel and weight, ...)?

Nandita Sharma · Accepted Answer · 2018-06-12 02:42:16Z

0

Use delete operator to remove the tel key from all objects in a loop

let list = [ 
{ 
  id: "247", 
  order_number: "21251", 
  tel: 13911111, 
  weight: "10kg" 
}, 
{ 
  id: "245", 
  order_number: "223", 
  tel: 31, 
  weight: "10kg" 
},
{ 
  id: "123", 
  order_number: "312312321", 
  tel: 3213123, 
  weight: "10kg" 
}
];
var list2 = JSON.parse(JSON.stringify(list));
for(i in list2) {
   delete list2[i].tel;
}

console.log(list2);
console.log(list);

edited Jun 12, 2018 at 2:42

answered Jun 12, 2018 at 2:36

Nandita Sharma

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2 Comments

Max K Over a year ago

The OP specified a new list. You have to first create a shallow copy of the array before deleting tel

Nandita Sharma Over a year ago

Updated the answer. please check now @MaxK

Andrew · Accepted Answer · 2018-06-12 02:44:09Z

0

As far as I know you aren't going to find a way without looping. If you think about it, in order to delete the key from every object it will need to loop over it no matter what even if it's just a loop disguised as a simple function.

As far as simplicity goes I would recommend using:

list.forEach(function(x){delete x.tel});

let list = [ 
{ 
  id: "247", 
  order_number: "21251", 
  tel: 13911111, 
  weight: "10kg" 
}, 
{ 
  id: "245", 
  order_number: "223", 
  tel: 31, 
  weight: "10kg" 
},
{ 
  id: "123", 
  order_number: "312312321", 
  tel: 3213123, 
  weight: "10kg" 
}
];


list.forEach(function(x){ delete x.tel });

console.log(list);

answered Jun 12, 2018 at 2:44

Andrew

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3 Comments

Sebastian Simon Over a year ago

You could do this without looping: Remove attribute for all objects in array. You could even do this with some setup of a Proxy.

Andrew Over a year ago

Correct me if I'm wrong, but in this case since every object has the key as opposed to a select few, wouldn't looping be just as efficient as another method because in both cases you will go to each index?

Sebastian Simon Over a year ago

You won’t iterate over each index, if you mutate a single prototype. You could also proxify the array or the objects and alter a few Proxy handlers to make the objects behave as if they didn’t have the tel property. Both approaches are O(1) rather than O(n).

Alexis Mateo · Accepted Answer · 2018-06-12 02:35:11Z

-2

You can use delete keyword.

delete myObject.prop

answered Jun 12, 2018 at 2:35

Alexis Mateo

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