Check if object contains all keys in array

Question

How can I most succinctly check if an object contains ALL of the keys specified in an array?

For example:

var arr = ["foo", "bar"];

var obj = {
  foo: 1,
  bar: "hello"
};

magic_function(arr, obj); // return true, all keys from array exist


var obj2 = {
  foo: 12,
  bar: "hi",
  test: "hey"
};

magic_function(arr, obj2); // return true, all keys from array exist,
                           // keys not specified in array don't matter


var obj3 = {
  foo: 5
};

magic_function(arr, obj3); // return false, "bar" is missing

@PraveenKumar, I was egging OP to atleast share pseudo code . As he has already asked 70+ question rather than just requesting complete code. Totally agree with K. Daniek comment — Satpal
– Satpal, Commented Jan 3, 2017 at 9:14

Cerbrus · Accepted Answer · 2020-01-20 11:33:05Z

32

This should do it:

const arr = ["foo", "bar"];

const obj = {
  foo: 1,
  bar: "hello"
};

const hasAllKeys = arr.every(item => obj.hasOwnProperty(item));

console.log(hasAllKeys);

Array.prototype.every() returns true if the passed function returns true for every item in the array.
Object.prototype.hasOwnProperty() is pretty self-explanatory.

edited Jan 20, 2020 at 11:33

answered Jan 3, 2017 at 9:08

Cerbrus

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3 Comments

Matt Fletcher Over a year ago

If obj additionally has baz = 'test', this will fail- so it's not inclusive that the keys and the array match perfectly

Cerbrus Over a year ago

@MattFletcher: This code only checks if all the key in the array are present on the object. It does not care about extra keys, as the original question explicitly demonstrated to be a requirement. This was never meant to be a perfect one-on-one match.

Matt Fletcher Over a year ago

I know, I just thought I'd highlight it for anyone else looking for exact key matching

Nina Scholz · Accepted Answer · 2017-01-03 09:31:27Z

9

You could iterate the array and check for the key with in operator

The in operator returns true if the specified property is in the specified object.

The difference between in operator and Object#hasOwnProperty is, in checks all properties, even the ones from the prototype, like toString (as in the example) and Object#hasOwnProperty checks only own properties, without the properties from the prototypes.

function checkKeys(keys, object) {
    return keys.every(function (key) {
        return key in object;
    });
}

function checkOwnKeys(keys, object) {
    return keys.every(function (key) {
        return object.hasOwnProperty(key);
    });
}

var arr = ["foo", "bar", "toString"],
    obj = { foo: 1, bar: "hello" };

console.log(checkKeys(arr, obj));                // true
console.log(checkOwnKeys(arr, obj));             // false
console.log(checkOwnKeys(["foo", "bar"], obj));  // true

edited Jan 3, 2017 at 9:31

answered Jan 3, 2017 at 9:08

Nina Scholz

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1 Comment

Cerbrus Over a year ago

I think it'd be useful to mention the difference between in and hasOwnProperty. Specifically: "The in operator returns true for properties in the prototype chain." Still, valid answer.

KARTHIKEYAN.A · Accepted Answer · 2023-06-14 09:29:25Z

0

We can check in the following way

const arr = ["foo", "bar"];

const obj = {
  foo: 1,
  bar: "hello"
};

const hasAllKeys = label => Object.prototype.hasOwnProperty.call(obj, label);

console.log(arr.every(item => hasAllKeys(item)));

answered Jun 14, 2023 at 9:29

KARTHIKEYAN.A

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