Override Strategies in localStorage? | by Sabesan Sathananthan

Picture by Lia Trevarthen on Unsplash

I usually wish to rewrite localStorage to implement a sure operate. What are the strategies to rewrite the strategies in localStorage? There are lots of builders who wish to rewrite the strategies in localStorageto comprehend the expiration time of the important thing, or to observe the learn and write of the important thing. So what are the strategies to override the strategies in localStorage. That is my forty third Medium article.

Many builders like the concept of ​​rewriting, first conserving the unique technique after which rewriting the tactic immediately on localStorage like beneath.

Nonetheless, this manner of writing will not be overriding the tactic setItem(), however so as to add a setItem attribute to localStorage. When the worth attribute of the tactic is asserted, the native setItem() technique is overwritten.

I haven’t examined it an excessive amount of, however in some browsers, this attribute will likely be ignored and inflicting our rewriting to fail.

If we glance carefully, setItem and getItem are inherited from Storage __proto__ pseudo property.

Then we immediately override the above localStorage.__proto__ technique.

This implements the true override of the setItem() technique.

However there’s nonetheless an issue right here. Each localStorage and sessionStorage inherit from Storage. After rewriting the properties or strategies on localStorage.__proto__, the strategies in sessionStorage are additionally rewritten.

We don’t immediately modify the tactic of localStorage itself, however wrap a layer on the skin, after which use localStorage to comprehend the storage operate on the backside layer.

On this method, the diploma of freedom is comparatively larger, and there’s no compatibility drawback in Part 1. Solely the title used has modified and the properties and strategies in localStorage are utterly blocked.

If you wish to use a customized object with out the pack then it’s good to implement all of the properties and strategies. It’s not doable to mock a technique alone just like the above.

Use Object.definePropertyor Proxyequal to utterly overriding the localStorage variable. Higher than Part 3 in that the title has not modified.

4.1 Direct protection, no impact

For those who use the next technique to cowl immediately, it’ll don’t have any impact.

window.localStorage = Object.create(null);  console.log(window.localStorage); //nonetheless native

We get the property descriptor of localStorage via Object.getOwnPropertyDescriptor. It may be discovered that there isn’t any writable: true attribute, which implies that localStorage will not be immediately writable.

4.2 Overriding with Object.defineProperty

Since there isn’t any writableattribute, we’ll add one to it. We are able to override localStorage with Object.defineProperty.

However you may’t use the above writing technique with one layer outdoors. For those who immediately give the above myLocalStorage to localStorage then it’ll generate infinite recursion (to keep away from deceptive, the incorrect writing technique is not going to be written right here).

I’ve made a backup of localStorage right here. For those who want a local technique then you can even function it.

On this article, we don’t particularly implement a operate resembling setting the expiration time. However speak about how one can rewrite localStorage or the strategies in it from one other perspective.

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