I usually need to rewrite localStorage to implement a sure operate. What are the strategies to rewrite the strategies in localStorage? There are a lot of 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 holding the unique methodology after which rewriting the tactic straight on localStorage like under.
Nevertheless, this manner of writing will not 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() methodology is overwritten.
I haven’t examined it an excessive amount of, however in some browsers, this attribute might be ignored and inflicting our rewriting to fail.
If we glance carefully, setItem and getItem are inherited from Storage __proto__ pseudo property.
Then we straight 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 straight modify the tactic of localStorage itself, however wrap a layer on the skin, after which use localStorage to comprehend the storage operate on the backside layer.
On this approach, 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 utterly blocked.
If you wish to use a customized object with out the pack then it is advisable to implement all of the properties and strategies. It isn’t attainable 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 identify has not modified.
4.1 Direct protection, no impact
When you use the next methodology to cowl straight, it should 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 is no such thing as a writable: true attribute, which signifies that localStorage will not be straight writable.
4.2 Overriding with Object.defineProperty
Since there is no such thing as a 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 methodology with one layer exterior. When you straight give the above myLocalStorage to localStorage then it should generate infinite recursion (to keep away from deceptive, the unsuitable writing methodology is not going to be written right here).
I’ve made a backup of localStorage right here. When you want a local methodology then you can even function it.
On this article, we don’t particularly implement a operate equivalent to setting the expiration time. However discuss methods to rewrite localStorage or the strategies in it from one other perspective.
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