I have the following JS object:

let obj = {
    'a': 1,
    'a-gaboom': 1,
    'b': 1,
    'b-gaboom': 1
};

I want to delete all fields that end with '-gaboom'.

I could do it manually with:

delete obj['a-gaboom'];
delete obj['b-gaboom'];

But I'd like to do it dynamically using a RegExp?

I have the following JS object:

let obj = {
    'a': 1,
    'a-gaboom': 1,
    'b': 1,
    'b-gaboom': 1
};

I want to delete all fields that end with '-gaboom'.

I could do it manually with:

delete obj['a-gaboom'];
delete obj['b-gaboom'];

But I'd like to do it dynamically using a RegExp?

• javascript
• regex
• algorithm
• object

Share Follow edited Jan 2, 2020 at 22:33 Danziger 21.2k66 gold badges5858 silver badges8989 bronze badges asked Jan 2, 2020 at 21:56 gkeenleygkeenley 7,4781717 gold badges7878 silver badges180180 bronze badges 1

• The current answers each assume that all -gabooms are at the root. If you need to turn {a: 1, b: {'c-gaboom': 2, d: 3, e: {f: 5, 'g-gaboo,': 6}}} into {a: 1, b: {d: 3, e: {f: 5}}} then it will still not be difficult, but is itself an interesting question. – Scott Sauyet Commented Feb 17, 2022 at 14:09

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3 Answers 3

Sorted by: Reset to default 5

You could do it using String.prototype.includes() or String.prototype.indexOf(), even though these will not take into account if -gaboom appears at the end of the key or at any other position, or using String.prototype.endsWith(), which will make sure the match is at the end of the key:

const obj = {
    'a': 1,
    'a-gaboom': 1,
    'b': 1,
    'b-gaboom': 1
};

for (const key in obj) {
  if (key.endsWith('-gaboom')) delete obj[key];
}

console.log(obj);

Anyway, this would be how it would look like with a RegExp, which does make sure -gaboom is at the end of the key by using $ and can easily be adapted to be way more flexible than any of the other alternatives above:

const obj = {
    'a': 1,
    'a-gaboom': 1,
    'b': 1,
    'b-gaboom': 1
};

for (const key in obj) {
  if (/-gaboom$/.test(key)) delete obj[key];
}

console.log(obj);

If you want to go for something more readable or a one-liner, I'd go for @OriDrori's approach or something similar using Array.prototype.reduce():

const obj = {
    'a': 1,
    'a-gaboom': 1,
    'b': 1,
    'b-gaboom': 1
};

const filtered = Object.keys(obj).filter(key => !/-gaboom$/.test(key)).reduce((acc, key) => {
  acc[key] = obj[key]; 
  return acc;
}, { });

console.log(filtered);

You can get the entries (array of [key, value] pairs) of the object with Object.entries(). Filter the array of entries, and keep only entries with a key that doesn't end with -gaboom. Convert back to an object via Object.fromEntries():

const obj = {'a': 1,'a-gaboom': 1,'b': 1,'b-gaboom': 1}

const result = Object.fromEntries(
  Object.entries(obj)
    .filter(([key]) => !key.endsWith('-gaboom'))
)

console.log(result)

taking a cue from the other answers, with this generic function it is possible to eliminate all the keys that verify a specific condition while mutating the original object.

deleteKeys = function (obj, fn) {
  Object.entries(obj)
    .filter(([key, value]) => fn(key, value))
    .forEach(([key]) => delete obj[key]);
};

const obj = {'a': 1,'a-gaboom': 1,'b': 1,'b-gaboom': 1};

deleteKeys(obj, (key) => !key.endsWith("-gaboom"));

console.log(obj)