Vue.js -数据数组为空时如何禁用按钮

data() {
  return {
    items: [] // 数据数组
  };
},
computed: {
  isDisabled() {
    return this.items.length === 0;
  }
}

<button v-bind:disabled="isDisabled">按钮</button>

data() {
  return {
    items: [] // 数据数组
  };
},
methods: {
  isDisabled() {
    return this.items.length === 0;
  }
}

<button v-bind:disabled="isDisabled()">按钮</button>

Vue.directive('disable-empty', {
  update: function(el, binding) {
    if (binding.value.length === 0) {
      el.disabled = true;
    } else {
      el.disabled = false;
    }
  }
});

<button v-disable-empty="items">按钮</button>