JavaScript+vue：自定义指令禁止表单输入非整数

              <!--<input type="number" min="0" max="10">-->
              <button style="padding:1px 4px" @click="amountChange(item, -1)">-</button>
                <input id="index" type="number" v-model="item.counter" v-number-only min="1" max="10">
                <!--<input type="text" v-model="item.counter" @input="formatCounter">-->
                <button style="padding:1px 4px" @click="amountChange(item, 1)">+</button>

directives: {
        numberOnly: {
            bind: function(el) {
                el.handler = function() {
                    var formatVal = /^\+?[1-9][0-9]*$/;
                    var val = el.value;
                    if(!formatVal.test(val)){
                        var reg = new RegExp(val,‘g‘);
                        el.value = val.replace(reg, 1);
                    }
                }
                el.addEventListener(‘input‘, el.handler)
            },
            unbind: function(el) {
                el.removeEventListener(‘input‘, el.handler)
            }
        }
    },