SIMO — Simple Mutable Objects

Simple Mutable Objects with Change Tracking for JavaScript

Installation

$ npm install simo

About

SIMO is a library for JavaScript (for use in the Node and Browser environment), providing simple mutable objects with the automatic and detailed tracking of changes. It allows one to craft mutable object graphs with the help of the JavaScript types Boolean, Number, String, RegExp, Date, Object, Array, Map, Set and Function. The object graphs are allowed to contain cycles and still can be serialized and unserialized.

Example

const simo = require("simo")

let obj = {
    foo: {
        bar: {
            boolean:  true,
            number:   42,
            string:   "foo",
            regexp:   /foo/i,
            date:     new Date("2020-01-01T00:00:00.000Z"),
            object:   { "k1": "v1", "k2": "v2" },
            array:    [ "v1", "v2" ],
            map:      new Map([[ "k1", "v1" ], [ "k2", "v2" ]]),
            set:      new Set([ "v1", "v2" ]),
            func:     function () { this.array.push("baz") }
        }
    }
}

console.log(obj)

obj = simo.cover(obj)
simo.observe(obj, (event, ...args) => {
    if (event === "change") {
        let [ path, target, property, op, valueOld, valueNew ] = args
        console.log(`change: ${path}: ${valueOld} --(${op})-> ${valueNew}`)
    }
})

obj.foo.bar.boolean = false
obj.foo.bar.number = 7
obj.foo.bar.regexp = /bar/
obj.foo.bar.string = "bar"
obj.foo.bar.date.setSeconds(1)
obj.foo.bar.object.k2 = "bar"
obj.foo.bar.array.push("bar")
obj.foo.bar.map.set("k2", "bar")
obj.foo.bar.map.delete("k1")
obj.foo.bar.set.add("v3")
obj.foo.bar.set.delete("v1")
obj.foo.bar.func()

console.log(obj)

Output:

{
  foo: {
    bar: {
      boolean: true,
      number: 42,
      string: 'foo',
      regexp: /foo/i,
      date: 2020-01-01T00:00:00.000Z,
      object: [Object],
      array: [Array],
      map: [Map],
      set: [Set],
      func: [Function: func]
    }
  }
}
change: foo.bar.boolean: true --(update)-> false
change: foo.bar.number: 42 --(update)-> 7
change: foo.bar.regexp: /foo/i --(update)-> /bar/
change: foo.bar.string: foo --(update)-> bar
change: foo.bar.date: 1577836800000 --(update)-> 1577836801000
change: foo.bar.object.k2: v2 --(update)-> bar
change: foo.bar.array.2: undefined --(create)-> bar
change: foo.bar.map.k2: v2 --(update)-> bar
change: foo.bar.map.k1: v1 --(delete)-> undefined
change: foo.bar.set.3: undefined --(create)-> v3
change: foo.bar.set.0: v1 --(delete)-> undefined
change: foo.bar.array.3: undefined --(create)-> baz
{
  foo: {
    bar: {
      boolean: false,
      number: 7,
      string: 'bar',
      regexp: /bar/,
      date: 2020-01-01T00:00:01.000Z,
      object: [Object],
      array: [Array],
      map: [Map],
      set: [Set],
      func: [Function: func]
    }
  }
}

Application Programming Interface

SIMO provides the following API:

• simo.cover(object: Object): SIMO
• simo.target(simo: SIMO): Object
• simo.uncover(simo: SIMO): Object
• simo.observe(simo: SIMO, callback: (event: String, args: any[]) => void): Symbol
• simo.unobserve(simo: SIMO, id: Symbol): void
• simo.sanity(): void

Implementation Notice

SIMO is written in ECMAScript 6 and relies on the Proxy, Reflect, Symbol, Map, and WeakMap APIs. There are two transpilation results: first, there is simo.browser.js for Browser environments. This is a size-compressed variant with included dependencies. Second, there is simo.node.js for Node.js environments. This is a variant without compression and included dependencies.

License

Copyright © 2020 Dr. Ralf S. Engelschall (http://engelschall.com/)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.