How to test if an object is a Proxy?

Question

I would like to test if a JavaScript object is a Proxy. The trivial approach

if (obj instanceof Proxy) ...

doesn\'t work here, nor does tra

Answer 1

Use window.postMessage() with try-catch

postMessage cannot serialize objects which incompatible with structured clone algorithm, like Proxy.

function isProxy(obj) {
    try {
        postMessage(obj, "*");
    } catch (error) {
        return error && error.code === 25; // DATA_CLONE_ERR
    }

    return false;
}