objClone

Copies an object. The copy is deep by default, so nothing inside it is shared with the original; pass deep: false to copy the top level only.

A structure that points back at itself is handled: every container is remembered while it is being copied, so a cycle is rebuilt with the same shape instead of recursing until the stack runs out.

Values that are not containers are returned as they are, so objClone(5) is 5.

What is copied

Containers are rebuilt; anything that cannot be rebuilt without knowing how it was made is handed back as it is.

	JavaScript	Dart	Python
Rebuilt, contents copied	plain object, Array, Map, Set	Map, List, Set	dict, list, tuple
Fresh copy	Date, RegExp	—	set (its members are immutable)
Handed back as it is	function, class instance	DateTime (immutable), class instance	datetime (immutable), class instance

Parameters

Name	Type	Required	Default
obj	anydynamicAny	●	–
The value to copy. A value that is not a container is returned as it is.
optionsnamedkeyword	CloneOptions	–	–
Copy options. See the table below.

namedThese parameters are passed as named parameters.

keywordThese parameters are passed as keyword arguments, or as a single dict in their place.

CloneOptions

Name	Type	Required	Default
deep	booleanbool	–	trueTrue
Copy everything inside the value. When falseFalse, only the top level is copied and nested containers stay shared with the original.

Returns

any

dynamic

Any

Examples

const source = { a: 1, b: { c: [1, 2] } };

const deep = objClone(source);
deep.b.c[0] = 99; // `source.b.c[0]` is still 1

const shallow = objClone(source, { deep: false });
shallow.b === source.b; // true, the nested object is shared

objClone([1, [2, 3]]); // Returns [1, [2, 3]]
objClone(5); // Returns 5

final source = {'a': 1, 'b': {'c': [1, 2]}};

final deep = objClone(source);
deep['b']['c'][0] = 99; // `source['b']['c'][0]` is still 1

final shallow = objClone(source, deep: false);
identical(shallow['b'], source['b']); // true, the nested map is shared

objClone([1, [2, 3]]); // Returns [1, [2, 3]]
objClone(5); // Returns 5

source = {'a': 1, 'b': {'c': [1, 2]}}

deep = objClone(source)
deep['b']['c'][0] = 99  # `source['b']['c'][0]` is still 1

shallow = objClone(source, {'deep': False})
shallow['b'] is source['b']  # True, the nested dict is shared

objClone([1, [2, 3]])  # Returns [1, [2, 3]]
objClone(5)  # Returns 5