Use localStorage with JavaScript.
I typically need to rewrite localStorage to implement a sure perform. 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 thought of ​​rewriting, first retaining the unique methodology after which rewriting the tactic instantly on localStorage like beneath.
Nevertheless, this manner of writing isn’t 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() methodology 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 intently, setItem and getItem are inherited from Storage __proto__ pseudo property.
Then we instantly override the above localStorage.__proto__ methodology.
This implements the true override of the setItem() methodology.
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 skin, after which use localStorage to understand the storage perform 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 utterly blocked.
If you wish to use a customized object with out the pack then it is advisable 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 utterly overriding the localStorage variable. Higher than Part 3 in that the identify has not modified.
4.1 Direct protection, no impact
When you use the next methodology to cowl instantly, it’s going to don’t have any impact.
window.localStorage = Object.create(null); console.log(window.localStorage); //nonetheless native
We get the property descriptor of localStorage by means of Object.getOwnPropertyDescriptor. It may be discovered that there isn’t any writable: true attribute, which implies that localStorage isn’t 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 may’t use the above writing methodology with one layer exterior. When you instantly give the above myLocalStorage to localStorage then it’s going to generate infinite recursion (to keep away from deceptive, the flawed writing methodology won’t be written right here).
I’ve made a backup of localStorage right here. When you want a local methodology then you may as well function it.
On this article, we don’t particularly implement a perform equivalent to setting the expiration time. However speak about learn how to rewrite localStorage or the strategies in it from one other perspective.
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