Use localStorage with JavaScript.
I usually need to rewrite localStorage to implement a sure perform. What are the strategies to rewrite the strategies in localStorage? There are numerous builders who need to rewrite the strategies in localStorageto comprehend 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 maintaining the unique technique after which rewriting the strategy immediately on localStorage like beneath.
Nevertheless, this fashion 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 asserted, 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 immediately 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 immediately modify the strategy of localStorage itself, however wrap a layer on the skin, after which use localStorage to comprehend the storage perform on the backside layer.
On this approach, the diploma of freedom is comparatively increased, and there’s no compatibility downside 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 essential implement all of the properties and strategies. It isn’t 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 title has not modified.
4.1 Direct protection, no impact
Should you use the next technique to cowl immediately, 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 way of Object.getOwnPropertyDescriptor. It may be discovered that there isn’t any writable: true attribute, which signifies that localStorage shouldn’t be immediately writable.
4.2 Overriding with Object.defineProperty
Since there isn’t any writableattribute, we’ll 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. Should you immediately give the above myLocalStorage to localStorage then it would generate infinite recursion (to keep away from deceptive, the unsuitable writing technique won’t be written right here).
I’ve made a backup of localStorage right here. Should you want a local technique then you can too function it.
On this article, we don’t particularly implement a perform reminiscent of setting the expiration time. However speak about how one can rewrite localStorage or the strategies in it from one other perspective.
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