Mutation & Cloning

By default, every method that changes data mutates the source object — the single exception is filter(), which always returns a fresh object.

const source = { a: 1 };
const result = Notation.create(source).set('b', 2).value;

source;          // » { a: 1, b: 2 }   (mutated)
result === source; // » true

Opt Out with clone()

Call clone() before any mutating method to work on a deep copy and leave the original untouched:

const source = { a: 1 };
const result = Notation.create(source).clone().set('b', 2).value;

source;            // » { a: 1 }         (untouched)
result;            // » { a: 1, b: 2 }
'b' in source;     // » false

What clone() Supports

Notation is for data objects with enumerable properties. clone() deeply copies:

• plain objects and arrays,
• primitives — String, Number, Boolean, Symbol, null, undefined,
• built-ins Date and RegExp.

Caution

Other enumerable values — functions, class instances, special objects — are copied by reference, not cloned. Non-enumerable properties and prototype chains are not preserved, and circular references aren’t supported.

For a full structural clone, clone first with a dedicated library and wrap the result:

import _ from 'lodash';
Notation.create(_.cloneDeep(source)).set('b', 2);