jeena/en.javascript.info
1
0
Fork 0
Code Issues Pull requests Projects Packages Wiki Activity Actions

fixes

Browse source
This commit is contained in:
Ilya Kantor 2019-06-20 16:16:45 +03:00
parent eeee9fedf7
commit 7697f95e24
4 changed files with 41 additions and 38 deletions
Download patch file Download diff file Expand all files Collapse all files

10
1-js/04-object-basics/04-object-methods/article.md
View file

@ -257,11 +257,11 @@ user.hi(); // John (the simple call works)
*/!*
```
On the last line there is a ternary operator that chooses either `user.hi` or `user.bye`. In this case the result is `user.hi`.
On the last line there is a conditinal operator that chooses either `user.hi` or `user.bye`. In this case the result is `user.hi`.
The method is immediately called with parentheses `()`. But it doesn't work right!
Then the method is immediately called with parentheses `()`. But it doesn't work right!
You can see that the call results in an error, because the value of `"this"` inside the call becomes `undefined`.
As you can see, the call results in an error, because the value of `"this"` inside the call becomes `undefined`.
This works (object dot method):
```js
@ -306,7 +306,7 @@ The Reference Type is a "specification type". We can't explicitly use it, but it
The value of Reference Type is a three-value combination `(base, name, strict)`, where:
- `base` is the object.
- `name` is the property.
- `name` is the property name.
- `strict` is true if `use strict` is in effect.
The result of a property access `user.hi` is not a function, but a value of Reference Type. For `user.hi` in strict mode it is:
@ -318,6 +318,8 @@ The result of a property access `user.hi` is not a function, but a value of Refe
When parentheses `()` are called on the Reference Type, they receive the full information about the object and its method, and can set the right `this` (`=user` in this case).
Reference type is a special "intermediary" internal type, with the purpose to pass information from dot `.` to calling parentheses `()`.
Any other operation like assignment `hi = user.hi` discards the reference type as a whole, takes the value of `user.hi` (a function) and passes it on. So any further operation "loses" `this`.
So, as the result, the value of `this` is only passed the right way if the function is called directly using a dot `obj.method()` or square brackets `obj['method']()` syntax (they do the same here). Later in this tutorial, we will learn various ways to solve this problem such as [func.bind()](/bind#solution-2-bind).