vant-weapp/dist/collapse/index.js

import { VantComponent } from '../common/component';
VantComponent({
    relation: {
        name: 'collapse-item',
        type: 'descendant',
        current: 'collapse',
    },
    props: {
        value: {
            type: null,
            observer: 'updateExpanded'
        },
        accordion: {
            type: Boolean,
            observer: 'updateExpanded'
        },
        border: {
            type: Boolean,
            value: true
        }
    },
    methods: {
        updateExpanded() {
            this.children.forEach((child) => {
                child.updateExpanded();
            });
        },
        switch(name, expanded) {
            const { accordion, value } = this.data;
            if (!accordion) {
                name = expanded
                    ? (value || []).concat(name)
                    : (value || []).filter((activeName) => activeName !== name);
            }
            else {
                name = expanded ? name : '';
            }
            this.$emit('change', name);
            this.$emit('input', name);
        }
    }
});