3 snippets across 2 stacks - JavaScript, Python
structuredClone(value)const original = [
{ name: "Ava", scores: [90, 85] },
{ name: "Leo", scores: [78, 92] },
];
const clone = structuredClone(original);
clone[0].scores.push(100);
console.log(original[0].scores); // [90, 85] (not affected)
console.log(clone[0].scores); // [90, 85, 100]Note structuredClone handles nested objects, arrays, Maps, Sets, Dates, RegExps, and more. Does NOT clone functions, DOM nodes, or prototypes.
const clone = structuredClone(value);const original = {
name: "Ava",
scores: [95, 88, 72],
metadata: { joined: new Date("2024-01-15") },
};
const clone = structuredClone(original);
clone.scores.push(100);
clone.metadata.joined.setFullYear(2025);
console.log(original.scores); // [95, 88, 72]
console.log(original.metadata.joined); // 2024-01-15 (unchanged)Note Built-in deep clone that handles Dates, Maps, Sets, RegExps, ArrayBuffers, circular references. Cannot clone functions, DOM nodes, or Error objects.
import copy
shallow = copy.copy(obj)
deep = copy.deepcopy(obj)import copy
original = [[1, 2], [3, 4]]
shallow = original.copy()
deep = copy.deepcopy(original)
original[0].append(99)
print(f"Original: {original}")
print(f"Shallow: {shallow}")
print(f"Deep: {deep}")Original: [[1, 2, 99], [3, 4]]
Shallow: [[1, 2, 99], [3, 4]]
Deep: [[1, 2], [3, 4]]Note list.copy(), dict.copy(), and slicing (lst[:]) all produce shallow copies. Nested mutable objects are still shared. Use copy.deepcopy() when you need fully independent nested structures.