muta

muta

Mutate your objects without mutating your objects

Overview:

• A thin wrapper around JS objects/arrays, using the Proxy API
• Protects data (similar to cloning), but without memory or CPU costs
• Mutations made to the wrapper can be either committed to the original object or thrown away
• All operations happen in O(1)

muta lets you wrap an object and make mutations to it, while only keeping in memory the unmodified original object and the mutation "patch". The wrapper can be accessed as if the mutations had made to the original object, and the mutations can be eventually committed to the original object if desired.

This module provides similar functionality to the jsondiffpatch and immer modules, although it is more efficient for large objects since we build the patch as the data is mutated rather than iterating through all the keys to compare at the end. In other words, jsondiffpatch and immer are both O(N), but muta is O(1).

Usage

npm install muta

let muta = require('muta')

let originalData = { foo: { bar: 123 } }

// `virtualData` appears to be the same as `originalData`,
let virtualData = muta(originalData)

// but changes you make to it don't affect `originalData`
virtualData.foo.bar += 1
console.log(originalData) // { foo: { bar: 123 } }
console.log(virtualData) // { foo: { bar: 124 } }

// view the mutations with muta.getPatch
console.log(muta.getPatch(virtualData)) // { foo: { [Symbol(assign)]: { bar: 124 } } }

// if you want to apply the changes,
// call muta.commit on the wrapper
muta.commit(virtualData)
console.log(originalData) // { foo: { bar: 124 } }