Fix - slice is not a function error in JavaScript

In this tutorial, we are going to learn about how to fix the slice is not a function error in JavaScript

When we use a Array.slice() method on a value which is not a type string or array, we will get the following error in our console.

Example:

const data =  1234;

data.slice(1);

Output:

"TypeError: data.slice is not a function

In the example above, we are using the slice() method on a data type Number. So, we are getting the the runtime error because the slice() method is only available for strings or arrays.

To fix the error, convert the value to a string or array before calling the slice() method on it or use it on correct data type.

Here is an example:

const data =  1234;

const result = data.toString().slice(1);
console.log(result);

Output:

"234"

In the example above, we used toString() method on a value before calling a slice() method.

The toString() helps us to convert the Number to String.

or we can check if the given value is an type string or array before calling the slice() method on it. So that we can avoid the runtime errors.

const data = 1234;

if (typeof data === "string"){
    data.slice(1);
}

const arr = [2, 3, 4];

if(Array.isArray(arr)){
    arr.slice(1);
}

Conclusion

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