How to Effectively Check for Set Local Storage Items in JavaScript?

Checking for Set Local Storage Items

When working with local storage in JavaScript, it's essential to be able to check if an item is set. To do this, we can leverage the localStorage.getItem() method.

One common approach is using a conditional statement like:

<code class="javascript">if (!(localStorage.getItem("infiniteScrollEnabled") == true || localStorage.getItem("infiniteScrollEnabled") == false)) {
  // Initialize or set default value
}</code>

However, this approach is not ideal as it relies on the presence of a truthy value in the storage item.

Instead, the getItem() method provides a more explicit way to check for existence. According to the WebStorage specification, if the item is not set, getItem() returns null:

If the given key does not exist in the list associated with the object then this method must return null.

Therefore, the recommended way to check if an item is set is:

<code class="javascript">if (localStorage.getItem("infiniteScrollEnabled") === null) {
  // Item is not set
}</code>

This method ensures that we can accurately determine whether an item is present in local storage, even when it's not explicitly set to a truthy or falsy value.

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