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React-compatible data-structure update utility



This is a mostly-compatible re-implementation of react's update function.

Usage (ES6)

import update from 'update-immutable';

let orig = { a: 1 };
let next = update(orig, { b: { $set: 2 } });

## next: { a: 1, b: 2 }
## orig: { a: 1 }


The following new features/bugfixes have been implemented:

  • Simple recursive implementation without dependencies

    The original version depends on react.

  • Implements $unset

    The react team refuses to merge this functionality. $unset is important for several use-cases, for example removing an item from a collection. $unset only works for objects, not arrays.

  • $unshift doesn't reverse

    The react version of $unshift unshifts each element in a loop, thereby reversing the provided list. This version fixes that bug and makes it work like perl's unshift.

  • Supports auto-vivification

    Auto-vivification allows you to modify a nested data structure even if the nesting data-structures don't yet exist. They will be created so as to satisfy the update. This simplifies many use-cases, for example you don't need to maintain an initial-state skeleton.


This module is mostly compatible with the react version except for the following:

  • Doesn't implement $apply

    This module is primarily intended for transferring incremental updates between browsers and server-side web apps. For this use case, $apply is not possible since functions cannot be serialised. If there is interest we may eventually implement $apply (pull requests welcome).

  • $unshift behaviour

    As described above, when passing multiple items in a single $unshift update, the order of the items is preserved, unlike react which reverses the list.


There is a companion perl module Update::Immutable that implements functionality identical to this module. This lets you process updates in the same way on both the server and the client (provided your server is implemented in perl that is).


(C) 2016 Doug Hoyte

2-clause BSD license