JS Standard Library

👯 Creates a fast deep clone of supported values, with circular reference support.

Info

The following types are supported for deep cloning:

Primitive types (except Symbols)
Plain Objects
Arrays
Maps & Sets
Dates
RegExps (lastIndex is not preserved)
RegExps (including lastIndex)
Errors
ArrayBuffers & TypedArrays
DataViews

Info

Circular References: Correctly handles circular references by keeping track of cloned objects.

Info

Functions and unsupported object instances are preserved by reference. If you need a generic platform clone for transferable objects, DOM/web APIs, or other specialized instances, use native structuredClone().

Info

Supported Error values preserve name, message, stack, cause, and custom own enumerable properties. Nested supported cause values are cloned deeply.

Syntax

TypeScript

import { clone } from '@opentf/std';

clone<T>(val: T): T

Parameters

val: The value to deeply clone.

Returns

A deep clone of supported values. Unsupported object instances and functions are returned by reference.

Examples

TypeScript

const input = { 
  arr: [1, 2, 3], 
  obj: { a: 'abc', b: 123 },
  date: new Date(),
  map: new Map([['a', 1], ['b', 2]]) 
};

const output = clone(input);

input === output; // false
output.arr === input.arr; // false
output.obj === input.obj; // false
output.map === input.map; // false
output.date.getTime() === input.date.getTime(); // true

class Box {
  constructor(value) {
    this.value = value;
  }
}

const boxed = new Box(1);
const clonedBoxed = clone({ boxed });
clonedBoxed.boxed === boxed; // true

// Circular references
const circular: any = { a: 1 };
circular.self = circular;
const clonedCircular = clone(circular);
clonedCircular.self === clonedCircular; // true