How does vuejs $emit add its own parameters to the parent component?

  javascript, vue.js

In subcomponents (i.e. ele-component components):
this.$emit(‘getAttrObj’, this.attrObj),
In the parent component:
<ele-component v-for=”(component,index) in componentArray” @getAttrObj=”getAttrObj”></ele- component>
methods: {

getAttrObj (attrObj, index) {
 
 bracket

bracket
Then the parent component can get this parameter of this.attrObj, but in addition to this, it also needs the index as the parameter of the method (the sequence number of the object in the array). although it can be passed to the child component first and then passed back to the child component, it feels a bit difficult.
Can you pass values directly from the parent component without overwriting this.attrObj passed from the child component? (that is, pass index to the getAttrObj method in the parent component)

@getAttrObj="getAttrObj($event, index)">