Use localStorage with JavaScript.
I typically need to rewrite localStorage to implement a sure operate. What are the strategies to rewrite the strategies in localStorage? There are numerous builders who need to rewrite the strategies in localStorageto understand 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 conserving the unique technique after which rewriting the tactic straight on localStorage like under.
Nonetheless, this manner of writing is just not 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 probably 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’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 understand the storage operate on the backside layer.
On this manner, the diploma of freedom is comparatively greater, and there’s no compatibility drawback in Part 1. Solely the title 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 it’s worthwhile to implement all of the properties and strategies. It isn’t potential 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 title has not modified.
4.1 Direct protection, no impact
In the event you use the next technique to cowl straight, it’ll haven’t 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 a writable: true attribute, which signifies that localStorage is just not straight writable.
4.2 Overriding with Object.defineProperty
Since there isn’t a writableattribute, we’ll add one to it. We are able to override localStorage with Object.defineProperty.
However you’ll be able to’t use the above writing technique with one layer outdoors. In the event you straight give the above myLocalStorage to localStorage then it’ll 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 the event you want a local technique then it’s also possible to function it.
On this article, we don’t particularly implement a operate akin 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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