You can use them conditionally to manipulate data before fetch or before storing. For example: you want to store the username when a person registers using the email id like userzyx@gmail.com then you can use it to generate username from it by truncating the later part and generate unique username which will be "userzyx" here.
Just open up your brains and see where further it can be used and possibilities are just unlimited.
class MyArray extends Array {
constructor(...args) {
super(...args);
return new Proxy(this, {
get: (target, name) => {
if (name && name.match && name.match(/^-\d+$/)) {
return Reflect.get(target, this.length + parseInt(name, 10));
}
return Reflect.get(target, name);
},
set: (target, name, value) => {
if (name && name.match && name.match(/^-\d+$/)) {
return Reflect.set(target, this.length + parseInt(name, 10), value);
}
return Reflect.set(target, name, value);
},
});
}
}
The CustomPage class 'extends' through the use of a proxy a Page and Browser class, while adding its own methods on top. The proxy mediates access to the Custompage instance, and the Page and Browser. When calling a method on CustomPage, it first looks to see if the method exists on the CustomPage instance, then the Browser instance, then the Page.
I had originally wanted to subclass Page, which is implemented by the Puppeteer library, but the Browser class had a dozen direct references to the Page class. I would have had to sublcass the Browser as well and override all those methods to instead reference my CustomPage. The proxy seemed like an appropriate solution.
pretty cool library that is only possible because of es6 proxys