Vue如何引入全局过滤器

// 时间戳转时分秒
function getformatDate (date, fmt) {
  if (/(y+)/.test(fmt)) {
      fmt = fmt.replace(RegExp.$1, (date.getFullYear() + '').substr(4 - RegExp.$1.length));
  }
  let o = {
      'M+': date.getMonth() + 1,
      'd+': date.getDate(),
      'h+': date.getHours(),
      'm+': date.getMinutes(),
      's+': date.getSeconds()
  };
  for (let k in o) {
      if (new RegExp(`(${k})`).test(fmt)) {
          let str = o[k] + '';
          fmt = fmt.replace(RegExp.$1, (RegExp.$1.length === 1) ? str : padLeftZero(str));
      }
  }
  return fmt;
};

function padLeftZero (str) {
  return ('00' + str).substr(str.length);
};

 // 时间过滤
 export function formatDate(time) {
  return getformatDate(new Date(time), "yyyy-MM-dd hh:mm");
}

import * as filters from './filters' // global filters

// register global utility filters.
Object.keys(filters).forEach(key => {
  Vue.filter(key, filters[key])
})

          <el-table :data="item.children" style="width: 100%">
            <el-table-column prop="title" label="标题"></el-table-column>
            <el-table-column prop="portName" label="上传单位"></el-table-column>
            <el-table-column prop="createdTime" label="上传时间">
              <template slot-scope="scope">{{scope.row.createdTime | formatDate}}</template>
            </el-table-column>
          </el-table>

filters: {
  timeForm(val) {
 
        if (typeof (value) == "undefined" || value === null) return "";
 
        let date = new Date(value);
        var y = date.getFullYear();
        var m = date.getMonth() + 1;
        var d = date.getDate();
        if (isNaN(y) && y != 0) {
          y = " ";
        }
        if (isNaN(m) && m != 0) {
          m = " ";
        } else {
          (m < 10 ? "0" + m : m);
        }
        if (isNaN(d) && d != 0) {
          d = " ";
        } else {
          (d < 10 ? "0" + d : d);
        }
 
        return y + "-" + m + "-" + d + " " + date.toTimeString().substr(0, 5);
}

Vue.filter('timeForm', function (value) {
  if (typeof (value) == "undefined" || value === null) return "";
 
  let date = new Date(value);
  var y = date.getFullYear();
  var m = date.getMonth() + 1;
  var d = date.getDate();
  if (isNaN(y) && y != 0) {
    y = " ";
  }
  if (isNaN(m) && m != 0) {
    m = " ";
  } else {
    (m < 10 ? "0" + m : m);
  }
  if (isNaN(d) && d != 0) {
    d = " ";
  } else {
    (d < 10 ? "0" + d : d);
  }
  return y + "-" + m + "-" + d + " " + date.toTimeString().substr(0, 5);
});
var timeForm = Vue.filter('timeForm');