Learn how to Override Strategies in localStorage? | by Sabesan Sathananthan


Use localStorage with JavaScript.

Picture by Lia Trevarthen on Unsplash

I usually need to rewrite localStorage to implement a sure perform. What are the strategies to rewrite the strategies in localStorage? There are lots of builders who need 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 retaining the unique technique after which rewriting the tactic straight on localStorage like beneath.

Nevertheless, this fashion of writing isn’t overriding the tactic setItem(), however so as to add a setItem attribute to localStorage. When the worth attribute of the tactic 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 carefully, setItem and getItem are inherited from Storage __proto__ pseudo property.

Then we straight 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 straight modify the tactic 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 manner, the diploma of freedom is comparatively larger, 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 could implement all of the properties and strategies. It isn’t 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

Should you use the next technique to cowl straight, it is going to haven’t 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 is no such thing as a writable: true attribute, which signifies that localStorage isn’t straight writable.

4.2 Overriding with Object.defineProperty

Since there is no such thing as a 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 exterior. Should you straight give the above myLocalStorage to localStorage then it is going to generate infinite recursion (to keep away from deceptive, the incorrect writing technique won’t be written right here).

I’ve made a backup of localStorage right here. Should you want a local technique then you may as well function it.

On this article, we don’t particularly implement a perform resembling setting the expiration time. However discuss the way to rewrite localStorage or the strategies in it from one other perspective.

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