penpal/lib/child/validateWindowIsIframe.js

A promise-based library for communicating with iframes via postMessage.

import { ErrorCode } from '../enums';
export default () => {
    if (window === window.top) {
        const error = new Error('connectToParent() must be called within an iframe');
        error.code = ErrorCode.NotInIframe;
        throw error;
    }
};