03-component-refactored.vue

<template>
  <div>
    <button type="button" @click="decrement">-</button> <!-- we removed the argument here -->
    <input type="text" :value="value" @input="setValue($event.target.value)" />
    <button type="button" @click="increment">+</button> <!-- we removed the argument here -->
  </div>
</template>

<script>
export default {
  ...
  methods: {
    ...
    increment() {
      this.setValue(this.value + this.step);
    },
    decrement() {
      this.setValue(this.value - this.step);
    },
  },
};
</script>