55 lines
1.3 KiB
Markdown
55 lines
1.3 KiB
Markdown
**Answer: an error.**
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Try it:
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```js run
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function makeUser() {
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return {
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name: "John",
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ref: this
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};
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};
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let user = makeUser();
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alert( user.ref.name ); // Error: Cannot read property 'name' of undefined
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```
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That's because rules that set `this` do not look at object definition. Only the moment of call matters.
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Here the value of `this` inside `makeUser()` is `undefined`, because it is called as a function, not as a method with "dot" syntax.
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The value of `this` is one for the whole function, code blocks and object literals do not affect it.
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So `ref: this` actually takes current `this` of the function.
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We can rewrite the function and return the same `this` with `undefined` value:
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```js run
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function makeUser(){
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return this; // this time there's no object literal
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}
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alert( makeUser().name ); // Error: Cannot read property 'name' of undefined
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```
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As you can see the result of `alert( makeUser().name )` is the same as the result of `alert( user.ref.name )` from the previous example.
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Here's the opposite case:
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```js run
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function makeUser() {
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return {
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name: "John",
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*!*
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ref() {
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return this;
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}
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*/!*
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};
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};
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let user = makeUser();
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alert( user.ref().name ); // John
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```
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Now it works, because `user.ref()` is a method. And the value of `this` is set to the object before dot `.`.
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