Vue.js swap array items
While @dfsq is correct about the use of index++ Vue doesn't recognize native mutations of arrays due to the inability to observe them. you have to use a mutation method to change them.
try this:
.then(() => { let rows = [this.forums[index], this.forums[index + 1]]; this.forums.splice(index, 2, rows[1], rows[0] );});I haven't tested it and I'll edit when I can.