Use localStorage with JavaScript.
I usually need to rewrite localStorage to implement a sure operate. What are the strategies to rewrite the strategies in localStorage? There are lots of 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 concept of rewriting, first retaining the unique technique after which rewriting the strategy instantly on localStorage like beneath.
Nonetheless, this manner of writing just isn’t 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 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 strategy 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 method, the diploma of freedom is comparatively increased, 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 it’s essential implement all of the properties and strategies. It’s not doable to mock a way 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 the event you 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 by way of Object.getOwnPropertyDescriptor. It may be discovered that there isn’t a writable: true attribute, which implies that localStorage just isn’t instantly 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 may’t use the above writing technique with one layer exterior. In the event you instantly give the above myLocalStorage to localStorage then it would generate infinite recursion (to keep away from deceptive, the fallacious writing technique is not going to 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 corresponding 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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