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minor fixes

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Ilya Kantor 2020-04-04 15:12:23 +03:00
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1-js/09-classes/01-class/article.md
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@ -333,11 +333,13 @@ Technically, they are processed after the constructor has done it's job.
### Making bound methods with class fields ### Making bound methods with class fields
Class fields together with arrow functions are often used to create methods with fixed `this`, that always references the object. Class fields together with arrow functions can be used to create "bound" methods, with fixed `this` that always references the object.
As demonstrated in the chapter <info:bind>, object methods, just like any functions, have a dynamic `this`. It depends on the context of the call. As demonstrated in the chapter <info:bind> functions in JavaScript have a dynamic `this`. It depends on the context of the call.
So, for instance, this code will show `undefined`: So if an object method is passed around and called in another context, `this` won't be a reference to its object any more.
For instance, this code will show `undefined`:
```js run ```js run
class Button { class Button {
@ -357,7 +359,9 @@ setTimeout(button.click, 1000); // undefined
*/!* */!*
``` ```
There are two ways to fix this, as discussed in the chapter <info:bind>: The problem is called "losing `this`".
There are two ways to fix it, as discussed in the chapter <info:bind>:
1. Pass a wrapper-function, such as `setTimeout(() => button.click(), 1000)`. 1. Pass a wrapper-function, such as `setTimeout(() => button.click(), 1000)`.
2. Bind the method to object in the constructor: 2. Bind the method to object in the constructor: