Expected Behavior

Obfuscated code behaves the same as the original. Here f() returns a new object on every call:

function f(o = { a: 1 }) { return o; }
f() === f(); // false

Current Behavior

transformObjectKeys: true changes the behavior of the code: f() === f() becomes true.

It moves the default object out of f(), so every call returns the same object:

var a = {};
a['a'] = 0x1;
function f(b = a) {
    return b;
}

Any mutation of that object leaks into later calls.

Steps to Reproduce

1. Open https://obfuscator.io/legacy-playground
2. Paste function f(o = { a: 1 }) { return o; } console.log(f() === f());
3. Turn on "Transform Object Keys", then click "Obfuscate"
4. Run the output. It prints true, but the original code prints false.

JavaScript Obfuscator Edition

• JavaScript Obfuscator Open Source

Your Environment

• Obfuscator version used: 5.8.0 (also 1.0.0 to 5.4.7)
• Node version used: 22.22.2

Stack trace

None. No error is thrown, the code silently behaves differently.

Minimal working example that will help to reproduce issue

const JavaScriptObfuscator = require('javascript-obfuscator');
const code = 'function f(o = { a: 1 }) { return o; } console.log(f() === f());';
eval(code); // false
eval(JavaScriptObfuscator.obfuscate(code, { transformObjectKeys: true }).getObfuscatedCode()); // true