I had the same problem.

To get rid of the warnings, the coupon tag in index.html needs to lose the v-on:applied="onCouponApplied" (or @applied="...", whichever you had from Episode 12) handler.

In both episodes, the blur event of the input called the coupon component's onCouponApplied method.

In episode 12, that method fired an 'applied' event which was captured by the coupon tag. This called the root component's onCouponApplied method, and the latter set the couponApplied property to true.

In episode 13, the coupon tag is bypassed: the coupon component's onCouponApplied method communicates the 'applied' event via the window.Event dispatcher directly to the root component's, who sends the alert (or could set the couponApplied property instead, to replicate the exact behaviour as in the previous episode).

The html should look like this:


<div id="root" class="content">
    <coupon></coupon>
    <p v-show="couponApplied">The coupon was applied</p>
</div>

and the javascript like this (I renamed window.Event to window.EventDispatcher but the rest should be the same as Jeff's code):


window.EventDispatcher = new class {
    constructor() {
        this.vue = new Vue();
    }

    fire(event, data = null) {
        this.vue.$emit(event, data);
    }

    listen(event, callback) {
        this.vue.$on(event, callback);
    }
};

Vue.component('coupon', {
   template: `<input placeholder="Enter your coupon code" @blur="onCouponApplied">`,

    methods: {
       onCouponApplied() {
           EventDispatcher.fire('applied');
       }
    }
});

new Vue({
    el: '#root',

    data: {
        couponApplied: false
    },

    created() {
        EventDispatcher.listen('applied', () => this.couponApplied = true);
    }

});

In short, the root component no longer has a onCouponApplied method because everything is handled by the listener registered with the Event dispatcher. The html, though, still included a potential call to that method: hence the warning, in the console, even though the code works.

Component Communication Example #2: Event Dispatcher

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