The sync modifier

Modifiers, such as

@click.stop="add"// Prevent propagation and bubbling
@click.prevent="add"// Block the default event
@click.stop.prevent="add"

// Different instructions have different modifiers
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.sync is also a modifier, which is the v-bind modifier

In the vue,

Components cannot modify external data for props,

This.$emit can emit events and pass parameters

$event gets the arguments to $emit

// In the parent component, you can use $event to get the value returned by the child component $emit
 <Child :money="total" v-on:update:money="total = $event"/>
In the child component, $emit is required to actively fire an event
  <button @click="$emit('update:money', money-100)"></button>
  
// The above can be abbreviated, namely
<Child :money.sync="total">
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