OrangeTree

Access, modify(copy-on-change) JavaScript object trees.

Orange trees can have fruits and flowers at the same time. OrangeTree project helps to modify object tree without mutation of original input. API use plain objects and arrays to store data. As modificaion applied to the tree, logic clones tree nodes from point of change to root of the tree to hold new changes while preserving original input immutable. To avoid unnecessary copies, it keeps track what nodes are already cloned in parallel Shadow tree structure.

JSON Pointer is used to refer to particular location in object tree. Rather then mutate object tree, API recreates branches keeping previous state immutable.

JSON Pointer implemented according RFC-6901 spec with little additon. In RFC you can use positive number in path to refer particular element of array, also you can use - to indicate new element of array to be created. This implementation make use of negative numbers to refer elements from the end of array. Such as -1 means last element, -2 - second from the end, and so forth ...

See: RFC 6901 - JavaScript Object Notation (JSON) Pointer - IETF Tools