Using includes() Method: If array contains an object/element can be determined by using includes() method. This method returns true if the array contains the object/element else return false. Example: html.
The _.has() method is used to check whether the path is a direct property of object or not. It returns true if path exists, else it returns false.
The simplest and fastest way to check if an item is present in an array is by using the Array. indexOf() method. This method searches the array for the given item and returns its index. If no item is found, it returns -1.
To check if a key exists in an object with Lodash and JavaScript, we can use the has method. We call has with the obj we want to check if the key exists in and the key we're searching for. Therefore, the first console log logs true and the 2nd one logs false .
The includes
(formerly called contains
and include
) method compares objects by reference (or more precisely, with ===
). Because the two object literals of {"b": 2}
in your example represent different instances, they are not equal. Notice:
({"b": 2} === {"b": 2})
> false
However, this will work because there is only one instance of {"b": 2}
:
var a = {"a": 1}, b = {"b": 2};
_.includes([a, b], b);
> true
On the other hand, the where
(deprecated in v4) and find
methods compare objects by their properties, so they don't require reference equality. As an alternative to includes
, you might want to try some
(also aliased as any
):
_.some([{"a": 1}, {"b": 2}], {"b": 2})
> true
Supplementing the answer by p.s.w.g
, here are three other ways for achieving this using lodash
4.17.5
, without using _.includes()
:
Say you want to add an object entry
to an array of objects numbers
, only if entry
does not exist already.
let numbers = [
{ to: 1, from: 2 },
{ to: 3, from: 4 },
{ to: 5, from: 6 },
{ to: 7, from: 8 },
{ to: 1, from: 2 } // intentionally added duplicate
];
let entry = { to: 1, from: 2 };
/*
* 1. This will return the *index of the first* element that matches:
*/
_.findIndex(numbers, (o) => { return _.isMatch(o, entry) });
// output: 0
/*
* 2. This will return the entry that matches. Even if the entry exists
* multiple time, it is only returned once.
*/
_.find(numbers, (o) => { return _.isMatch(o, entry) });
// output: {to: 1, from: 2}
/*
* 3. This will return an array of objects containing all the matches.
* If an entry exists multiple times, if is returned multiple times.
*/
_.filter(numbers, _.matches(entry));
// output: [{to: 1, from: 2}, {to: 1, from: 2}]
If you want to return a Boolean
, in the first case, you can check the index that is being returned:
_.findIndex(numbers, (o) => { return _.isMatch(o, entry) }) > -1;
// output: true
You could use find
to solve your problem
https://lodash.com/docs/#find
const data = [{"a": 1}, {"b": 2}]
const item = {"b": 2}
find(data, item)
// > true
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