vue directive input限制小数点位数，及更新v-model

 //无小数点
 //保留两位小数点


Vue.directive('enterNumber', {
    bind: function(el, { value = 2 }) {
        el = el.nodeName == "INPUT" ? el : el.children[0]
        var RegStr = value == 0 ? `^[\\+\\-]?\\d+\\d{0,0}` : `^[\\+\\-]?\\d+\\.?\\d{0,${value}}`;
        el.addEventListener('keyup', function() {
            el.value = el.value.match(new RegExp(RegStr, 'g'));
            el.dispatchEvent(new Event('input'))
        })
    }
})