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 various 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 concept of ​​rewriting, first retaining the unique methodology after which rewriting the tactic immediately on localStorage like under.
Nonetheless, this manner of writing just 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 can be ignored and inflicting our rewriting to fail.
If we glance carefully, setItem and getItem are inherited from Storage __proto__ pseudo property.
Then we immediately override the above localStorage.__proto__ methodology.
This implements the actual override of the setItem() methodology.
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 immediately 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 larger, 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 you have to implement all of the properties and strategies. It’s not attainable to mock a technique 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 methodology to cowl immediately, it is going to 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 just isn’t immediately writable.
4.2 Overriding with Object.defineProperty
Since there isn’t a writableattribute, we are going to add one to it. We are able to override localStorage with Object.defineProperty.
However you may’t use the above writing methodology with one layer outdoors. In the event you immediately give the above myLocalStorage to localStorage then it is going to generate infinite recursion (to keep away from deceptive, the incorrect writing methodology won’t be written right here).
I’ve made a backup of localStorage right here. In the event you want a local methodology then it’s also possible to function it.
On this article, we don’t particularly implement a operate similar to setting the expiration time. However discuss how one can rewrite localStorage or the strategies in it from one other perspective.
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