How to check if an array includes an object in JavaScript?

In most higher-level programming languages, arrays come with built-in methods which can be used to access and manipulate data present inside arrays. JavaScript also has such methods which will be the topic of this article. Specifically, the methods which can be used to check if an object with a particular property/value is present inside an array.

JavaScript offers many methods whose functionality can be used to check for objects inside arrays. We’ll look at most of them in great detail:

arr.some() Method

The some() method takes a function as an argument which checks if any element of the array contains a specific property value. If that property value is found then the method returns true:

Else it returns false:

arr.includes() Method

The includes method takes an object as an argument and returns true if it is present inside an array:

let emp1 = {firstName:"John", lastName:"Doe", age:39};
let emp2 = {firstName:"Adam", lastName:"Smith", age:40};
let employees = [emp1, emp2];

let found = employees.includes(emp1);

console.log(found);

It is important to note that the argument object and the object inside the array should be the same. Different objects with same values will return false:

arr.find() Method

The find() method is similar to the some() as it checks for specific property values but if found, it returns the object instead of true value:

If the object is not present then the find() method returns undefined:

arr.filter() Method

The filter() method can be applied on an array to get a list of all the objects that pass certain conditions:

arr.findIndex() Method

The findIndex() method will check for specific property value and return the index of the found object:

If the object is not found then it returns -1:

Conclusion

In this write-up we went over several ways of checking if an array contains an object in JavaScript. All of these methods have a few differences in how they work. These differences were mentioned and comprehensively discussed in the post above.