How to solve includes is not a function in JavaScript

In this tutorial, we are going to learn about how to solve the TypeError includes is not a function in JavaScript

When we use a includes() method on a value which is not an data type array or string we will get the following errors in our console.

Example:

const age = 23;

age.includes(2);

Output:

"TypeError: age.includes is not a function

In the example above, we are getting the error because we are using the includes() method on a data type Number. The includes() method is only available for strings and arrays.

To solve the error, we are converting the given value to a string or array before calling the includes() method on it.

Here is an example:

const age = 23;
const result = age.toString().includes('2');

console.log(result); // true

For arrays, before calling a includes() method.we can check if the given value is a data type array or not using the Array.isArray() method.

const arr = [2, 3, 4];

if(Array.isArray(arr)){
    console.log(arr.includes(3)); // true
}

Conclusion

The “includes is not a function” error occurs when we call a includes() method on a value other than the strings or arrays. To solve the error convert the value to a string or array before calling the includes() method on it.