one billion two hundred and twelve million three hundred and twelve thousand three hundred and twenty-one

 Parent component ：
computed: {
    

showFooter() {
    
      return (this.componentName === 'firstLink' && !this.hideBtn) || this.componentName === 'survey' || (this.componentName === 'form' && !this.disabled);
    },
}

methods: {
    
     //  How to make this showFooter  Received this this.hideBtn The value changes ？
      showBtn(params) {
    
      if (params) {
    
        this.$set(this, 'hideBtn', true);
      } else {
    
        this.$set(this, 'hideBtn', false);
      }
    },
}

 From the sub assembly 
contactVisible(newVal) {
    
      this.$emit('showBtn', newVal);
  }