JavaScript Internals (521 Qs)•Part 6: Async Internals, Memory, Microtasks & Web APIs (329 - 403)
Is PostMessage secure
Yes, postMessages can be considered very secure as long as the programmer/developer is careful about checking the origin and source of an arriving message. But if you try to send/receive a message without verifying its source will create cross-site scripting attacks.
Practical Code Example
javascript
// PostMessage is only secure if you explicitly validate event.origin:
// Vulnerable:
// window.addEventListener('message', e => eval(e.data));
// Secure:
window.addEventListener('message', (event) => {
if (event.origin !== 'https://trusted-domain.com') return; // Enforce origin check!
console.log('Secure data:', event.data);
});