Emit child function in parent (VUE)

emit_child_function_in_parent.vue

<template>
  <div id="app">
    <child-component ref="childComponent"></child-component>
    <button @click="someParentAction">Click</button>  
  </div>
</template>

<script>
/* --Child Component*/
let ChildComponent = {
  template: '<div>{{value}}</div>',
  data: function () {
    return {
      value: 0
    };
  },
  methods: {
    setValue(value) {
        this.value = value;
    }
  }
}

/* --Parent Component*/
new Vue({
  el: '#app',
  components: {ChildComponent},
  methods: {
    someParentAction() {
        this.$refs.childComponent.setValue(2.0);
    }
  }
})
</script>