Use localStorage with JavaScript.
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 protecting the unique technique after which rewriting the tactic instantly on localStorage like beneath.
Nonetheless, this fashion of writing shouldn’t 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 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 instantly 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 instantly modify the tactic of localStorage itself, however wrap a layer on the surface, after which use localStorage to comprehend the storage operate 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 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 you must 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 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 instantly, it would 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 shouldn’t be instantly 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 possibly can’t use the above writing technique with one layer outdoors. For those who instantly give the above myLocalStorage to localStorage then it would generate infinite recursion (to keep away from deceptive, the mistaken writing technique won’t be written right here).
I’ve made a backup of localStorage right here. For those who want a local technique then you too can function it.
On this article, we don’t particularly implement a operate comparable to setting the expiration time. However speak about find out how to rewrite localStorage or the strategies in it from one other perspective.
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