How fix Object is of type 'unknown'?

 mounted () {
            this.$nextTick(function () {
              this.$refs.task1.classList.add('increase')
            })

CodePudding user response：

Try to cast the referenced element as follows :

 mounted () {
            this.$nextTick(()=> {
              (this.$refs.task1 as HTMLElement).classList.add('increase')
            })