index.js

import { VantComponent } from '../common/component';
VantComponent({
    classes: [
        'main-item-class',
        'content-item-class',
        'main-active-class',
        'content-active-class',
        'main-disabled-class',
        'content-disabled-class'
    ],
    props: {
        items: {
            type: Array,
            observer: 'updateSubItems'
        },
        activeId: null,
        mainActiveIndex: {
            type: Number,
            value: 0,
            observer: 'updateSubItems'
        },
        height: {
            type: [Number, String],
            value: 300
        },
        max: {
            type: Number,
            value: Infinity
        }
    },
    data: {
        subItems: []
    },
    methods: {
        // 当一个子项被选择时
        onSelectItem(event) {
            const { item } = event.currentTarget.dataset;
            const isArray = Array.isArray(this.data.activeId);
            // 判断有没有超出右侧选择的最大数
            const isOverMax = isArray && this.data.activeId.length >= this.data.max;
            // 判断该项有没有被选中, 如果有被选中，则忽视是否超出的条件
            const isSelected = isArray
                ? this.data.activeId.indexOf(item.id) > -1
                : this.data.activeId === item.id;
            if (!item.disabled && (!isOverMax || isSelected)) {
                this.$emit('click-item', item);
            }
        },
        // 当一个导航被点击时
        onClickNav(event) {
            const index = event.detail;
            const item = this.data.items[index];
            if (!item.disabled) {
                this.$emit('click-nav', { index });
            }
        },
        // 更新子项列表
        updateSubItems() {
            const { items, mainActiveIndex } = this.data;
            const { children = [] } = items[mainActiveIndex] || {};
            return this.set({ subItems: children });
        }
    }
});