Use localStorage with JavaScript.
I typically wish to rewrite localStorage to implement a sure operate. What are the strategies to rewrite the strategies in localStorage? There are various builders who wish 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 conserving the unique technique after which rewriting the strategy instantly on localStorage like beneath.
Nevertheless, this fashion of writing is just not overriding the strategy setItem(), however so as to add a setItem attribute to localStorage. When the worth attribute of the strategy is asserted, 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 carefully, setItem and getItem are inherited from Storage __proto__ pseudo property.
Then we instantly override the above localStorage.__proto__ technique.
This implements the true 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 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 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’ll want to 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
For those who use the next technique to cowl instantly, it would 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 isn’t a writable: true attribute, which signifies that localStorage is just not 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’ll be able to’t use the above writing technique with one layer exterior. For those who instantly give the above myLocalStorage to localStorage then it would generate infinite recursion (to keep away from deceptive, the improper writing technique is not going to 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 equivalent to setting the expiration time. However speak about how you can rewrite localStorage or the strategies in it from one other perspective.
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