vant-weapp/packages/collapse-item/index.ts

import { VantComponent } from '../common/component';

VantComponent({
  classes: ['title-class', 'content-class'],

  relation: {
    name: 'collapse',
    type: 'ancestor',
    current: 'collapse-item',
  },

  props: {
    name: null,
    title: null,
    value: null,
    icon: String,
    label: String,
    disabled: Boolean,
    clickable: Boolean,
    border: {
      type: Boolean,
      value: true,
    },
    isLink: {
      type: Boolean,
      value: true,
    },
  },

  data: {
    expanded: false,
  },

  created() {
    this.animation = wx.createAnimation({
      duration: 0,
      timingFunction: 'ease-in-out',
    });
  },

  mounted() {
    this.updateExpanded();

    this.inited = true;
  },

  methods: {
    updateExpanded() {
      if (!this.parent) {
        return Promise.resolve();
      }

      const { value, accordion } = this.parent.data;
      const { children = [] } = this.parent;
      const { name } = this.data;

      const index = children.indexOf(this);
      const currentName = name == null ? index : name;

      const expanded = accordion
        ? value === currentName
        : (value || []).some((name: string | number) => name === currentName);

      if (expanded !== this.data.expanded) {
        this.updateStyle(expanded);
      }

      this.setData({ index, expanded });
    },

    updateStyle(expanded: boolean) {
      const { inited } = this;
      this.getRect('.van-collapse-item__content')
        .then(
          (rect: WechatMiniprogram.BoundingClientRectCallbackResult) =>
            rect.height
        )
        .then((height: number) => {
          const { animation } = this;

          if (expanded) {
            if (height === 0) {
              animation.height('auto').top(1).step();
            } else {
              animation
                .height(height)
                .top(1)
                .step({
                  duration: inited ? 300 : 1,
                })
                .height('auto')
                .step();
            }

            this.setData({
              animation: animation.export(),
            });
            return;
          }

          animation.height(height).top(0).step({ duration: 1 }).height(0).step({
            duration: 300,
          });

          this.setData({
            animation: animation.export(),
          });
        });
    },

    onClick() {
      if (this.data.disabled) {
        return;
      }

      const { name, expanded } = this.data;
      const index = this.parent.children.indexOf(this);
      const currentName = name == null ? index : name;

      this.parent.switch(currentName, !expanded);
    },
  },
});