27 lines
752 B
Markdown
27 lines
752 B
Markdown
|
|
# Observable
|
|
|
|
Create a function `makeObservable(target)` that "makes the object observable" by returning a proxy.
|
|
|
|
Here's how it should work:
|
|
|
|
```js run
|
|
function makeObservable(target) {
|
|
/* your code */
|
|
}
|
|
|
|
let user = {};
|
|
user = makeObservable(user);
|
|
|
|
user.observe((key, value) => {
|
|
alert(`SET ${key}=${value}`);
|
|
});
|
|
|
|
user.name = "John"; // alerts: SET name=John
|
|
```
|
|
|
|
In other words, an object returned by `makeObservable` has the method `observe(handler)` that allows to add `handler` function to be called on a property change.
|
|
|
|
Whenever a property changes, `handler(key, value)` is called with the name and value o the property.
|
|
|
|
P.S. In this task, please handle only writing to a property. Other operations can be implemented in a similar way.
|