Use localStorage with JavaScript.
I usually wish to rewrite localStorage to implement a sure perform. What are the strategies to rewrite the strategies in localStorage? There are numerous 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 thought of rewriting, first holding the unique technique after which rewriting the strategy straight on localStorage like under.
Nevertheless, this manner of writing shouldn’t be 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 will likely be ignored and inflicting our rewriting to fail.
If we glance intently, setItem and getItem are inherited from Storage __proto__ pseudo property.
Then we straight 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 straight modify the strategy of localStorage itself, however wrap a layer on the surface, after which use localStorage to comprehend the storage perform on the backside layer.
On this approach, the diploma of freedom is comparatively greater, and there’s no compatibility downside 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 should implement all of the properties and strategies. It isn’t doable 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
When you use the next technique to cowl straight, it can don’t have any impact.
window.localStorage = Object.create(null); console.log(window.localStorage); //nonetheless nativeWe get the property descriptor of localStorage via Object.getOwnPropertyDescriptor. It may be discovered that there isn’t a writable: true attribute, which implies that localStorage shouldn’t be straight writable.
4.2 Overriding with Object.defineProperty
Since there isn’t a writableattribute, we are going to add one to it. We are able to override localStorage with Object.defineProperty.
However you possibly can’t use the above writing technique with one layer exterior. When you straight give the above myLocalStorage to localStorage then it can generate infinite recursion (to keep away from deceptive, the mistaken writing technique is not going to be written right here).
I’ve made a backup of localStorage right here. When you want a local technique then you may as well function it.
On this article, we don’t particularly implement a perform similar to setting the expiration time. However discuss learn how to rewrite localStorage or the strategies in it from one other perspective.
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