html5怎样进行跨域通信

export default class Messager {

    constructor(win, targetOrigin) {

        this.win = win;

        this.targetOrigin = targetOrigin;

        this.actions = {};

        window.addEventListener('message', this.handleMessageListener, false);

    }

    handleMessageListener = event => {

        if (!event.data || !event.data.type) {

            return;

        }

        const type = event.data.type;

        if (!this.actions[type]) {

            return console.warn(`${type}: missing listener`);

        }

        this.actions[type](event.data.value);

    }

    on = (type, cb) => {

        this.actions[type] = cb;

        return this;

    }

    emit = (type, value) => {

        this.win.postMessage({

            type, value

        }, this.targetOrigin);

        return this;

    }

    destroy() {

        window.removeEventListener('message', this.handleMessageListener);

    }

}