here example: https://jsfiddle.net/alekzonder/1zcLkuwq/ vue.js 2.1.10 steps in example: 1. press "unshift new" button 2. then press "set bold" with 0 index in input problem: item with index 1 is bold after Array.unshift in data if remove `:key=item.id` in template with v-for, all works right bug or feature?