router-mixin-all.js

const router = {
  map (stuff) {
    console.log(JSON.stringify(stuff))
  }
}
const ComponentA = {
  mixins: [{}]
}
const ComponentB = {
  mixins: []
}
const ComponentC = {}

const myMixin = {
  ready () {
    console.log('foo')
  }
}

const mixThemAll = (obj, ...mixins) => {
  return Object.entries(obj).reduce((container, [key, data]) => {
    if (data.component.mixins) {
      if (data.component.mixins instanceof Array) {
        data.component.mixins.push(...mixins)
      } else {
        throw new Error('component.mixins is not an Array!')
      }
    } else {
      data.component.mixins = [...mixins]
    }

    container[key] = data
    return container
  }, {})
}

const routerComponents = {
  '/a': {
    component: ComponentA
  },
  '/b': {
    component: ComponentB
  },
  '/c': {
    component: {
      template: '<h1>Hello</h1>'
    }
  }
}

router.map(mixThemAll(routerComponents, myMixin, myMixin, myMixin))