title: vue after $emit callback finished
body: <p>In the compoent ,when call <code>$emit('callback', params)</code> finished, I need the returned value. Someone can help?</p>
  <p>vueComponent:</p>
  <pre><code>    methods: {
          test: function () {
              if(this.$emit('cb', param1)){
                  // this not working
                  console.log('return true')
              }else{
                  console.log('return false')
              }
          }
      }
  </code></pre>
  <p>vueRoot:</p>
  <pre><code>methods: {
          cb: function () {
              return true;
          }
      }
  </code></pre>