[Vuejs]-How to get selected value with append-outer click on vue?

The + element is inside v-for. That means you have access to the current object. So, if you have v-for="card in cards", you can access card.id where you initialize the click listener – @click="doStuffWithSelectedValue"
—> You can change that line to @click="doStuffWithSelectedValue(card.id)" and the use it as parameter inside method’s declaration.