Freeze-tag NPM

freeze-tag

A simple, fast, and highly customizable way to deep freeze objects, avoiding mutation.

Features

Recursive - Begins at your root object and goes all the way down. No data structure left behind.
Fast - Places mutation handler on your objects, which is way faster than Object.freeze-ing them.
Simple API - Freezing is one extra function call. Then you can copy them for mutation using whatever method you normally (I hope!) use to copy mutable objects.
Customizable - A simple options parameter allows you to set rules for handling mutations.

freeze-tag creates a deep proxy of your object, affecting the ways you can mutate: set, delete, setPropertyOf, and defineProperty.

For each of these, you can decide whether you want your objects to be "tagged" and console.error() if they're mutated, or for them to be completely "frozen" so that you can't mutate them at all. Or both! Or neither.

Usage with Redux:

freeze-tag was designed so that you could cetainly use it alone, but Redux was the use case in mind. Use the tiny redux-freeze-tag library to immutabalize your reducers with one line of code in one file.

Vanilla Usage:

npm install freeze-tag

var freeze = require('freeze-tag').freeze;

Now you have a function you can use anywhere in your app.

var frozenObj = freeze(obj);

And to unfreeze and mutate your object, you can simply Object.assign or Object Spread or however you like to do it.

var unfrozen = Object.assign({}, frozenObj, {whatIsBestInLife: 'tooling'});

Configuration

You can also customize behavior by importing the freeze-tag() function, to which you can pass in an options object and get back a customized freeze() function.

var freezeTag = require('freeze-tag').freezeTag;

var freeze = freezeTag({
  set: true,
  delete: true,
  defineProperty: false,
  setPrototypeOf: true
});

This example would give you a freeze() function that affects the set, delete, and setPrototypeOf mutations, but not the defineProperty mutation. And you use it just like you did before.

var frozenObj = freeze(obj);

The default is for set to be true and the other three false. If you think delete is important to avoid as well (and some people do use it liberally), set that to be true as well. The initial focus with this library has been speed, but even full immutability with defineProperty and setPrototypeOf handlers turned on doesn't actually come with much cost unless your objects are extraordinarily huge.

You can also substitute an object for a true to change the default behavior, if you want to really drill down. By default, freeze() will both 'tag' mutations for console.error-ing and 'freeze' mutations from happening at all. But if you want to do only one or the other, you can set that like so:

var freeze = freezeTag({
  set: {tag: false, freeze: true},
  delete: true,
  defineProperty: false,
  setPrototypeOf: {tag: true, freeze: false}
});

Whether you choose freeze only, tag only, or both makes no difference whatsoever to your app's speed. The only speed difference is between false and any other setting. So feel free to customize the behavior to whatever would help your team most.

What's Next

TODO: 1. Continue to fiddle with this README. 2. Make the console.errors a bit more readable. 3. Add toggleable protection from production use. 4. Clean up the code and make it a bit prettier. 5. Remember what else I wanted to change.