Stress Testing React Easy State
The Power of ES6 Proxies
Last week I announced React Easy State: a state management library based on ES6 Proxies. The announcement mentioned something, which deserves an article on its own.
You just have to deal with plain objects and React components and let Easy State keep them in sync for you.
This was not a rhetorical statement, and I would like to prove it with a simple App.
This was the last none vanilla code snippet in the whole article. It creates a
users array and exposes it globally on the
UsersApp maps the array to a simple React view.
We will mutate the
users array from the developer console in increasingly exotic ways and see how
UsersApp react. Hint: it should automatically re-render when users are added, removed or modified.
#1. Warm up: Adding a new user
Let’s start by adding a simple user to the
users array and then changing it’s email address.
Easy State knows that
UsersApp iterates the
users array during its render and it knows that
user.email is rendered for every user. From this it deduces, that
UsersApp should re-render after each operation.
If you feel like it, follow along with the live example app. Don’t be surprised, it’s an empty page. You can fill it with users from your developer console — like I did.
#2. Dynamic properties
The first example was not that impressive. Let’s see something that is exclusive to ES6 Proxies, by pasting these lines — one by one — to the console.
This time the new user was added by
users = newUser instead of
push and at first it didn’t have an email. Adding new properties dynamically— like the email — can only be tracked by ES6 Proxies. Older state management libraries won’t re-render the app in these cases.
delete is another operation that was impossible to track until recently. Easy State re-renders the
UsersApp if you delete a property which is used during its render.
#3. Property accessors and enumeration
It’s time to take a deeper dive. For this example we will need some preparation code.
Dave is a user with multiple email addresses. A property getter is used to dynamically generate his email, by enumerating the emails object and constructing a string from it.
Easy State knows that Dave’s email is generated from all of the properties in his
emails collection. If a new email is added to the collection, it re-renders the
UsersApp to reflect it. The same happens when an email is deleted.
#4. The final boss: Inheritance
Let’s see what happens if we throw in prototypal inheritance to the mix. This example will also need a preparation script.
John — the new user — inherits his name and email from Ann — the second user.
- If we delete John’s name, it falls back to
Annbecause of the inheritance.
- Then editing Ann’s name changes both Ann’s and John’s name.
- Finally we add an own name for
Easy State re-renders the App after each of these operations — since all of them results in a different view.
If you enjoyed this article please check the Github repo of Easy State and leave a star before you go.