Vue v-for object does not update after data changed

Question

I use vue version 2.5.x

Example like below.

No matter how hard I click \"add item\" the button, no item show in page.

But the \"add item version 2\" wo

Answer 1

Replace : this.items[this.count.toString()] = this.count;

with Vue.set(this.items,this.count.toString(),this.count);

let app = new Vue({
  el: "#app",
  data: {
    items: {},
    count: 0,
  },
  methods: {
    add() {
        Vue.set(this.items,this.count.toString(),this.count);

      this.count++;
      console.log(this.items);
    },
    add2() {
      let items = {}
      items[this.count.toString()] = this.count;
      this.items = items;
      this.count++;
      console.log(this.items);
    }
  }
})

https://jsfiddle.net/zbb57ozv/

It's a limitations of javascript or Vue js caveat . check out section Change Detection Caveats of vue document for more information : Vue-Js Reactivity In Depth