VUX components in the checker component, there are many holes, please tell us how to solve?

<checker v-model="equipmentcheck" type="checkbox" default-item-class="item" 
                selected-item-class="item-selected">
                    <checker-item v-for="item in equipments" :key="item.id" :value="item.id" @on-item-click="onItemClick()">
                        {{item.name}}
                    </checker-item>
                </checker>

The

js function is

onItemClick () {
              console.log(this.equipmentcheck.length);
          },

question 1: when the result is printed, the length is 0 when it is checked the first time, and 2 is displayed normally when the second is selected, that is to say, there is no case that the length is 1. How is this going on?

question 2:click event does not seem to determine whether it is currently selected or not? Please tell me how to judge whether it is selected or not. -sharp-sharp-sharp topic description

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