class Scroll {static get top() {return Math.max(document.documentElement.scrollTop || document.body.scrollTop);}static get clientHeight() {return Math.max(document.documentElement.clientHeight || document.body.clientHeight);}static get clientWidth() {return Math.max(document.documentElement.clientWidth || document.body.clientWidth);}static get height() {return Math.max(document.documentElement.scrollHeight || document.body.scrollHeight);}static get width() {return Math.max(document.documentElement.scrollWidth || document.body.scrollWidth);}static get bottom() {return Scroll.height - Scroll.clientHeight - Scroll.top;}
}

const on = (function () {if (document.addEventListener) {return function (element, event, handler) {if (element && event && handler) {element.addEventListener(event, handler, false);}};} else {return function (element, event, handler) {if (element && event && handler) {element.attachEvent('on' + event, handler);}};}
})();

/*** 降低事件执行频率*/
const downsampler = (function () {let result = null;return function (time, func) {if (!result) {result = setTimeout(function () {func();result = null;}, time);}}
})();

Vue.directive("infinite-scroll", {bind(el, binding, vnode) {on(window, 'scroll', function () {if (typeof binding.value === "function" && Scroll.bottom <= 50) {   // 小于50就触发downsampler(50, binding.value);  // 降低触发频率
            }})}
});

<div class="app" v-infinite-scroll="coupon"><template v-for="item in goods"><p>{{item}}</p></template>
</div>

        let v = new Vue({el: ".app",data(){return {goods:[]}},methods: {coupon() {this.goods.push("你呵呵")}}})