answer-mini/wechat-app/static/vant/dropdown-item/index.js

import { VantComponent } from '../common/component';
VantComponent({
  field: true,
  relation: {
    name: 'dropdown-menu',
    type: 'ancestor',
    current: 'dropdown-item',
    linked() {
      this.updateDataFromParent();
    },
  },
  props: {
    value: {
      type: null,
      observer: 'rerender',
    },
    title: {
      type: String,
      observer: 'rerender',
    },
    disabled: Boolean,
    titleClass: {
      type: String,
      observer: 'rerender',
    },
    options: {
      type: Array,
      value: [],
      observer: 'rerender',
    },
    popupStyle: String,
  },
  data: {
    transition: true,
    showPopup: false,
    showWrapper: false,
    displayTitle: '',
  },
  methods: {
    rerender() {
      wx.nextTick(() => {
        this.parent && this.parent.updateItemListData();
      });
    },
    updateDataFromParent() {
      if (this.parent) {
        const {
          overlay,
          duration,
          activeColor,
          closeOnClickOverlay,
          direction,
        } = this.parent.data;
        this.setData({
          overlay,
          duration,
          activeColor,
          closeOnClickOverlay,
          direction,
        });
      }
    },
    onOpen() {
      this.$emit('open');
    },
    onOpened() {
      this.$emit('opened');
    },
    onClose() {
      this.$emit('close');
    },
    onClosed() {
      this.$emit('closed');
      this.setData({ showWrapper: false });
    },
    onOptionTap(event) {
      const { option } = event.currentTarget.dataset;
      const { value } = option;
      const shouldEmitChange = this.data.value !== value;
      this.setData({ showPopup: false, value });
      this.$emit('close');
      this.rerender();
      if (shouldEmitChange) {
        this.$emit('change', value);
      }
    },
    toggle(show, options = {}) {
      const { showPopup } = this.data;
      if (typeof show !== 'boolean') {
        show = !showPopup;
      }
      if (show === showPopup) {
        return;
      }
      this.setData({
        transition: !options.immediate,
        showPopup: show,
      });
      if (show) {
        this.parent.getChildWrapperStyle().then((wrapperStyle) => {
          this.setData({ wrapperStyle, showWrapper: true });
          this.rerender();
        });
      } else {
        this.rerender();
      }
    },
  },
});