I want to do a deep copy of an object which also has function as keys.

So I do

deepCopy = structuredClone(existingObjWithFns);

However when this runs, I get the below error:

Uncaught (in promise) DOMException: Failed to execute 'structuredClone' on 'Window': function MyFunction()

I want to do a deep copy of an object which also has function as keys.

So I do

deepCopy = structuredClone(existingObjWithFns);

However when this runs, I get the below error:

Uncaught (in promise) DOMException: Failed to execute 'structuredClone' on 'Window': function MyFunction()

• javascript
• ecmascript-6
• deep-copy
• structured-clone

Share Improve this question Follow edited Mar 28, 2023 at 12:41 halfer 20.4k1919 gold badges109109 silver badges202202 bronze badges asked Mar 22, 2023 at 8:26 copenndthagencopenndthagen 50.9k105105 gold badges313313 silver badges491491 bronze badges 1

• 4 Yep, you can't structuredClone a function. – AKX Commented Mar 22, 2023 at 8:33

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2 Answers 2

Sorted by: Reset to default 7

Function objects cannot be duplicated by the structured clone algorithm; attempting to throws a DataCloneError exception.

for more information, you can read MDN

if you want to deep clone nested objects, you should make a function to check the type of all of them and copy them one by one.

Lodash deepClone work with all types, function,s and Symbol copied by reference I suggest that you use Lodash.

but with the object.assign() you can do it faster:

const target = { a: () => { return 1 }, b: 2 };
const source = { b: 4, c: 5 };

const returnedTarget = Object.assign(target, source);

console.log(target);
// Expected output: Object { a: 1, b: 4, c: 5 }

console.log(returnedTarget === target);
// Expected output: true

for more information about object cloning you can follow this link

structuredClone throwing error in browser, so i found alternate way using lodash npm package

npm i lodash 

const _ = require('lodash');
   
var obj = {
    anyField: 23
};
   
// Here is structured clone so it won't get copied
var deepCopy = _.cloneDeep(obj);
   
console.log('Comparing original with'
    + ' deep ', obj === deepCopy);
   
obj.anyField = 10; // Changing original value
   
console.log('After changing original value');
   
console.log("Original value ", obj);
   
console.log("Deep Copy value ", deepCopy);