Delete vs. Splice: Which JavaScript Method Should You Use to Remove Array Elements?

Deleting Array Elements in JavaScript: delete vs splice

Working with arrays in JavaScript often involves the need to remove elements. Two methods that can be used for this are the delete operator and the Array.splice method. While both can achieve the goal of deleting an element, they differ significantly in their implementation and implications.

delete Operator

The delete operator deletes the property of an object or array at the specified index. However, unlike an object, an array is a special type of object that keeps track of its indices. When an element is deleted from an array via the delete operator, it does not automatically reindex or adjust the length of the array.

Consider the example:

const myArray = ['a', 'b', 'c', 'd'];
delete myArray[1];

After executing this code, the myArray[1] property is deleted, but the array still has a length of 4. The deleted element is marked as "empty" in the Chrome dev tools, giving the impression that it has been set to undefined. However, this is not the case; the property is simply missing from the array.

Array.splice Method

The Array.splice method, on the other hand, actually removes the element from the array, reindexes subsequent elements, and updates the length of the array.

Consider the example:

const myArray = ['a', 'b', 'c', 'd'];
myArray.splice(1, 1);

In this case, the element at index 1 (which has the value "b") is removed from the array. The remaining elements are reindexed, and the length of the array is reduced to 3.

When to Use delete or splice

Based on their behavior, it is generally recommended to use the Array.splice method for deleting array elements. The delete operator can lead to confusion because it leaves empty slots in the array, which may not be the desired behavior. The splice method, on the other hand, provides a cleaner and more intuitive way to remove elements while maintaining the correct structure and length of the array.

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