vue2.0 passes new data (slots) like child components

Parent component 
<componentA> 
    <p>123</p>
 </componentA> 
child component

<template> 
    <div> 
        {{boonook}} 
        <button @click ="emitMyEvent">emit</button> 
       <slot></slot>
     </div> 
</template> 
There can also be a default value in the slot, when After adding content to the parent component, it will be overwritten, if not, the content in the slot will be displayed by default