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minor fixes

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This commit is contained in:
Ilya Kantor 2022-03-24 08:42:12 +03:00
parent bf6d3c959e
commit 9e210b78d7
1 changed files with 2 additions and 2 deletions
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1-js/04-object-basics/07-optional-chaining/article.md
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@ -108,7 +108,7 @@ E.g. in `user?.address.street.name` the `?.` allows `user` to safely be `null/un
```warn header="Don't overuse the optional chaining" ```warn header="Don't overuse the optional chaining"
We should use `?.` only where it's ok that something doesn't exist. We should use `?.` only where it's ok that something doesn't exist.
For example, if according to our coding logic `user` object must exist, but `address` is optional, then we should write `user.address?.street`, but not `user?.address?.street`. For example, if according to our code logic `user` object must exist, but `address` is optional, then we should write `user.address?.street`, but not `user?.address?.street`.
So, if `user` happens to be undefined due to a mistake, we'll see a programming error about it and fix it. Otherwise, coding errors can be silenced where not appropriate, and become more difficult to debug. So, if `user` happens to be undefined due to a mistake, we'll see a programming error about it and fix it. Otherwise, coding errors can be silenced where not appropriate, and become more difficult to debug.
``` ```
@ -179,7 +179,7 @@ let user1 = {
firstName: "John" firstName: "John"
}; };
let user2 = null; let user2 = null;
alert( user1?.[key] ); // John alert( user1?.[key] ); // John
alert( user2?.[key] ); // undefined alert( user2?.[key] ); // undefined