JavaScript - Built in Function to Delete Multiple Keys in an Object? - Stack Overflow

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In JavaScript, I can delete an object's key with

delete myObject[myKey];

Is there an efficient way to delete multiple keys using one line? Something that looks like:

multiDelete myObject[keyOne, keyTwo, keyThree];

In JavaScript, I can delete an object's key with

delete myObject[myKey];

Is there an efficient way to delete multiple keys using one line? Something that looks like:

multiDelete myObject[keyOne, keyTwo, keyThree];

• javascript

Share Improve this question Follow edited Sep 23, 2022 at 20:13 Robin De Schepper 6,30644 gold badges4242 silver badges6363 bronze badges asked Sep 12, 2015 at 2:34 user4596113user4596113 2

• 1 Efficient from what perspective? Using delete is already inefficient in first place. – zerkms Commented Sep 12, 2015 at 2:39
• 1 but not all of the values in the parent key that encapsulate the keys I want to delete Could you clarify? What do you mean by "parent key" or "encapsulate the keys"? – user663031 Commented Sep 12, 2015 at 5:13

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9 Answers 9

Sorted by: Reset to default 110

Here's a one-liner similar to what you're requesting.

var obj = {a: 1, b: 2, c: 3, d: 4, e: 5 };

['c', 'e'].forEach(e => delete obj[e]);

// obj is now {a:1, b:2, d:4}

You can also use Object Destructuring.

const obj = {
        a: 'dog',
        b: 'cat',
        c: 'mouse',
        d: 'cow',
        e: 'horse',
    };
const {a, e, ...updatedObject} = obj;

// output
console.log(updatedObject)

There is one simple fix using the library lodash.

The _.omit function takes your object and an array of keys that you want to remove and returns a new object with all the properties of the original object except those mentioned in the array.

This is a neat way of removing keys as using this you get a new object and the original object remains untouched. This avoids the problem of mutation where if we removed the keys in the original object all the other parts of code using that object might have a tendency to break or introduce bugs in the code.

Example:

var obj = {x:1, y:2, z:3};
var result = _.omit(obj, ['x','y']);
console.log(result);

//Output
result = {z:3};

Link for the documentation of the same Click Here

There is no built in js function to delete multiple keys yet, you can use any library for this such as underscore.js to do this.

_.omit({name: 'moe', age: 50, userid: 'moe1'}, 'userid');
=> {name: 'moe', age: 50}

//or you can use function to filter keys 

_.omit({name: 'moe', age: 50, userid: 'moe1'}, function(value, key, object){
  return _.isNumber(value);
});
=> {name: 'moe', userid: 'moe1'}

There is no built-in function, but one way you could do it is to add the multidelete method to the Object prototype. It's perhaps a little bit overkill, but you might find it useful.

if (!('multidelete' in Object.prototype)) {
    Object.defineProperty(Object.prototype, 'multidelete', {
        value: function () {
            for (var i = 0; i < arguments.length; i++) {
                delete this[arguments[i]];
            }
        }
    });
}

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };

obj.multidelete('c', 'e'); // { a: 1, b: 2, d: 4 };

DEMO

If you want a solution that feels built-in, you could add a utility function that works like Object.defineProperties(), so you can add properties to a given object, but now also delete properties by handing in a null property descriptor.

Object.defineProperties() throws an error if a property descriptor is not an object, so we can safely use a "falsy" value to indicate that the property is to be deleted.

Here is the code:

function unDefineProperties(obj, propertyDescriptors) {
  const [normalDescriptors, toBeDeletedDescriptors] =
    partition(Object.entries(propertyDescriptors),([_, descriptor]) => descriptor);
  Object.defineProperties(obj, Object.fromEntries(normalDescriptors));
  toBeDeletedDescriptors.forEach(([name, _]) => delete obj[name]);
  return obj;
}

The name of the function is supposed to be read as "(un)define properties", i.e. "define or delete properties".

It splits the given propertyDescriptors into the "normal" ones with a non-"falsy" value and the "to-be-deleted" ones with a "falsy" value, using the utility function partition (defined in the code snippet below, borrowed from this answer).

It then calls Object.defineProperties() with a property descriptors object reconstructed from the "normal" entries.

After that (because the first step may fail due to incorrect property descriptors), all "to-be-deleted" entries delete the corresponding properties in obj.

Finally, obj is returned, to mimic the convenient behavior of Object.defineProperties().

The resulting function is compatible with the original Object.defineProperties() (of course apart from the behavior for "falsy" property descriptors) and thus could be used as a replacement for that original function. If you want to do so, for consistency, you should also replace Object.defineProperty() (singular!) by a similar function that handles a "falsy" property descriptor by deleting the corresponding property (left as an exercise for the reader ;-)).

Here is the complete code with a usage example:

const partition = (array, filter) =>
    array.reduce(([pass, fail], e, i) =>
        ((filter(e, i, array) ? pass : fail).push(e), [pass, fail]),
        [[], []]);

function unDefineProperties(obj, propertyDescriptors) {
  const [normalDescriptors, toBeDeletedDescriptors] =
    partition(Object.entries(propertyDescriptors),([_, descriptor]) => descriptor);
  Object.defineProperties(obj, Object.fromEntries(normalDescriptors));
  toBeDeletedDescriptors.forEach(([name, _]) => delete obj[name]);
  return obj;
}

// Usage example:

const obj = { a: 'A', b: 'B', c: 'C'};

unDefineProperties(obj, {
  a: null,
  c: null,
  d: { value: "D", enumerable: true }
});

console.log(obj); // logs { "b": "B", "d": "D" }

You may create an array of keys to delete by a string and iterate over the object to delete them

var obj = {key1: 1, key2: 2, key3: 3 };

"key1 key2 key3".split(" ").forEach(e => delete obj[e]);

A non-mutating fix that creates a top-level clone of the input object (like the libraries mentioned in other answers):

function omitKeys(obj, keys) {
  const r = { ...obj };
  keys.forEach(k => delete r[k]);
  return r;
}

I found another solution using a loop through Object.entries() which may be helpful:

var array = {1:'a',2:'b',3:'c',4:'d'};

for (var [key, char] of Object.entries(array)) {
   delete array[key];
}

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