boxed-immutable

boxed-immutable

:warning: Version 0.5.0 has renamed functions in the util internal library in the process of reducing conflict and to make them more consistent with their actual function. The API is evolving and will still change as its idiosyncrasies and limitations are discovered in use. The boxed-in proxy is fairly stable but may add new magic properties and eventually retire unused or little use properties. boxed-out proxy gained iteration helpers to mimic ones available for arrays.

Immutable proxy wrapper with auto-vivification of intermediate objects/arrays with syntactic sugar to keep access/modification to deeply nested properties looking almost the same as plain object property access. Flexible data transforms to massage or validate the data on boxed state creation or on property changes: Transforms

1. Create a boxed-immutable object proxy from any value, including undefined then access and/or modify its direct and nested properties, without concern to whether intermediate values are objects/arrays or whether they exist. The final result will either reflect the value of an actual property or be undefined if any intermediate properties were undefined or invalid.

2. Modify any direct or nested properties without affecting the original object/array. It will be shallow copied on first modification of any property. All further modifications will be done on the copy.

3. Get the full modified array/object or just the changed properties to pass to state updater such as Redux dispatch() or React component's setState().

Install

Use npm to install.

npm install boxed-immutable --save

Usage

The concept behind this module is to create a protective box around a value: to box it.

For values inside the box, all properties return a proxy that does the job of keeping immutable originals intact, track modified properties, auto-vivify containers when properties are set and provide magic properties.

Any value can be boxed, traversed several levels deep into its property tree and at any point take that property value out of the box. All access from this point on to the property and its nested properties is on regular JavaScript object properties. If any intermediate property access was invalid, the value of the unboxed property will be undefined.

Some code to show how it all comes together. Each example will be a continuation of the code in the previous example, unless it starts with the require('boxed-immutable')

const _$ = require('boxed-immutable').box;

let state = {
    isLoaded: false,
    isLoading: false,
    appSettings: {
        title: "The Title",
    }
};

let state_$ = _$(state);
let dashboardName = "overview";
let showDashboard;
let title;

showDashboard = state_$.appSettings.dashboards[dashboardName].showDashboard(); // result is undefined
title = state_$.appSettings.title(); // result is "The Title"

Modifying properties is even easier because they can be set without unboxing. It might seem easier just to bang away on the unboxed state object but then you will not get immutability barrier, same value optimization, TypeError and ReferenceError protection and parent container instantiation. The following is a no-op:

state_$.isLoaded = false;

On the other hand the next line will cause the proxy to make a shallow copy of the boxed value and then set its isLoading property to true.

state_$.isLoading = true; // this will shallow copy the underlying object and set its property

Now for some fun examples that would not work with JavaScript objects:

state_$.appSettings.dashboards[dashboardName].showDashboard = true;
state_$.appSettings.dashboards[dashboardName].dashboardTitle = "Overview";

let newState = state_$;

At this point newState will be the same as if you did:

let newState = {
    isLoaded: false,
    isLoading: true,
    appSettings: {
        title: "The Title",
        dashboards: {
            overview: {
                showDashboard: true,
                dashboardTitle: "Overview",
            },
        },
    },
};

The rest of this file was moved to the wiki for greater leg room, boxed-immutable wiki

License

MIT, see LICENSE.md for details.