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HomeSoftware EngineeringThe way to Override Strategies in localStorage? | by Sabesan Sathananthan

The way to Override Strategies in localStorage? | by Sabesan Sathananthan


Use localStorage with JavaScript.

Picture by Lia Trevarthen on Unsplash

I usually wish to rewrite localStorage to implement a sure perform. What are the strategies to rewrite the strategies in localStorage? There are various builders who wish to rewrite the strategies in localStorageto comprehend the expiration time of the important thing, or to watch 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 thought of ​​rewriting, first maintaining the unique technique after which rewriting the strategy immediately on localStorage like beneath.

Nevertheless, this fashion of writing is just not overriding the strategy setItem(), however so as to add a setItem attribute to localStorage. When the worth attribute of the strategy is said, the native setItem() technique is overwritten.

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

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

Then we immediately override the above localStorage.__proto__ technique.

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

However there may be 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 strategy of localStorage itself, however wrap a layer on the skin, after which use localStorage to comprehend the storage perform on the backside layer.

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

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

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

4.1 Direct protection, no impact

In case you use the next technique to cowl immediately, it is going to don’t have any impact.

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

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

4.2 Overriding with Object.defineProperty

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

However you may’t use the above writing technique with one layer exterior. In case you immediately give the above myLocalStorage to localStorage then it is going to generate infinite recursion (to keep away from deceptive, the improper writing technique won’t be written right here).

I’ve made a backup of localStorage right here. In case you want a local technique then you can too function it.

On this article, we don’t particularly implement a perform akin to setting the expiration time. However speak about tips on how to rewrite localStorage or the strategies in it from one other perspective.

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