SOURCE

var app = new Vue({
    el: '#app',
    data() {
        return {
            value: ''
        }
    },
    directives: {
        enterNumber: {
            bind: (el, binding) => {
                // 指令作用在 element-input 节点，对应原生 div.el-input (真实input节点的父节点)
                if (el.tagName.toLocaleUpperCase() !== 'INPUT') {
                    el = el.getElementsByTagName('input')[0]
                }
                el.value = el.value.replace(/[^0-9]+/g, '')
                el.onkeypress = e => {
                    const code = String.fromCharCode(e.keyCode || e.which)
                    return /[\d]/.test(code) || e.which === 8
                }
                el.oninput = () => {
                    el.value = el.value.replace(/[^0-9]+/g, '')
                }
            }
        }
    }
})

<div id="app">
    <div>{{value}}</div>
    <el-input v-model="value" v-enter-number placeholder="请输入"></el-input>
</div>