vant-weapp/packages/radio-group/index.ts

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

VantComponent({
  field: true,

  relation: useChildren('radio', function (target) {
    this.updateChild(target);
  }),

  props: {
    value: {
      type: null,
      observer: 'updateChildren',
    },
    disabled: {
      type: Boolean,
      observer: 'updateChildren',
    },
  },

  methods: {
    updateChildren() {
      (
        this.children || []
      ).forEach((child: WechatMiniprogram.Component.TrivialInstance) =>
        this.updateChild(child)
      );
    },

    updateChild(child: WechatMiniprogram.Component.TrivialInstance) {
      const { value, disabled } = this.data;
      child.setData({
        value,
        disabled: disabled || child.data.disabled,
      });
    },
  },
});