as-mutable

as-mutable

as-mutable offers an ergonomic way to mutate data without touching the original source. It's a handy helper at circumstance, say when you work with redux, where you need to mutate native js data struct (object/array) while keeping the original source immutable.

Usage

import { asMutable, getValue } from 'as-mutable'

const mutableCopy = asMutable(source)
// do whatever you want to the `mutableCopy`,
// mutate it! it's ok as long as you keep its reference.

// own prop:
mutableCopy.foo = 'bar'
// deep nested object
mutableCopy.zoo.lo = 'gy'
// deep nested array
mutableCopy.things.push({ useful: true })
// new prop
mutableCopy.usefulThings = mutableCopy.things.filter(item => item.useful)

// when you're done, call `getValue()` to get the result.
const result = getValue(mutableCopy)

Caveats

• In order to work, as-mutable requires present of ES Proxy in the runtime.
• It's designed for plain js object and array, object with custom prototype should be fine most of the time, supposing you don't do crazy things.
• No support for ES Map/Set/WeekMap. These data structs are meant to be mutable at source, don't see the point to keep them immutable.