Edit in JSFiddle

var originalComponent = Vue.component('original', {
  created: function () {
    console.log('original component created!')
  },
  methods: {
    hello: function () {
      console.log('hello from mixin!')
    }
  }
})

var extComponent = Vue.extend({
  extends: [originalComponent],
  created: function() {
    console.log('override old created!')
    this.hello()
  },
  methods: {
    hello: function() {
      console.log('hello from self!')
    }
  }
})
new extComponent()