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This commit is contained in:
Ilya Kantor 2019-07-16 19:23:00 +03:00
parent 67e317cee9
commit 52ef3256c9
16 changed files with 100 additions and 96 deletions
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6-data-storage/02-localstorage/article.md
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@ -61,7 +61,7 @@ alert( localStorage.test ); // 2
delete localStorage.test;
```
That's allowed for historical reasons, and mostly works, but generally not recommended for two reasons:
That's allowed for historical reasons, and mostly works, but generally not recommended, because:
1. If the key is user-generated, it can be anything, like `length` or `toString`, or another built-in method of `localStorage`. In that case `getItem/setItem` work fine, while object-like access fails:
```js run
@ -157,7 +157,7 @@ Properties and methods are the same, but it's much more limited:
- The `sessionStorage` exists only within the current browser tab.
- Another tab with the same page will have a different storage.
- But it is shared between iframes in the tab (assuming they come from the same origin).
- But it is shared between iframes in the same tab (assuming they come from the same origin).
- The data survives page refresh, but not closing/opening the tab.
Let's see that in action.
@ -212,7 +212,7 @@ localStorage.setItem('now', Date.now());
Please note that the event also contains: `event.url` -- the url of the document where the data was updated.
Also, `event.storageArea` contains the storage object -- the event is the same for both `sessionStorage` and `localStorage`, so `storageArea` references the one that was modified. We may even want to set something back in it, to "respond" to a change.
Also, `event.storageArea` contains the storage object -- the event is the same for both `sessionStorage` and `localStorage`, so `event.storageArea` references the one that was modified. We may even want to set something back in it, to "respond" to a change.
**That allows different windows from the same origin to exchange messages.**
@ -245,5 +245,5 @@ API:
Storage event:
- Triggers on `setItem`, `removeItem`, `clear` calls.
- Contains all the data about the operation, the document `url` and the storage object.
- Contains all the data about the operation (`key/oldValue/newValue`), the document `url` and the storage object `storageArea`.
- Triggers on all `window` objects that have access to the storage except the one that generated it (within a tab for `sessionStorage`, globally for `localStorage`).