Props vs Data in Vue.js

Props vs Data in Vue.js

In this tutorial, we are going to learn about the difference between props and data in vue with the help of examples.

Props

  • Props are used to pass the data to child components from parent components.
  • Props are read-only (We can’t mutate props).
  • Props are registered inside vue components by using props property.

Example:

Welcome.vue
<template>
   <h1>Welcome {{name}}</h1></template>

<script>
   export default{
       props:['name'] //name prop is registered   }
</script>

In this example, we registered name inside Welcome component, registered props can be used just like data properties inside a template.

Let’s pass the data to Welcome component.

App.vue
<template>
   <div id="app">
      <Welcome name="Gowtham"/>   </div>
</tempalte>

Here we passed data to the Welcome component by using name prop.

Data

The data we defined inside vue components are independent to that component, so that we can’t access or mutate the data from other components.

The only way to access the component data from the other components is by using props.

Data is mutable in vue.js so that if we update the data properties vue will automatically re-render your component with the updated changes.

Example:

Let’s consider we have two components named Welcome.vue and App.vue.

Welcome.vue
<template>
   <h1>Welcome {{name}}</h1></template>

<script>
   export default{
       props:['name'] //name prop is registered   }
</script>
App.vue
<template>
  <div>
    <Welcome :name="name" />    <button @click="changeName">Change name</button>
  </div>
</template>

<script>
import Welcome from "./welcome.vue";
export default {
  data: function() {
    return {
      name: "Gowtham"    };
  },
  methods: {
    changeName() {
      this.name = "Vue";
    }
  },
  components: { Welcome }
};
</script>

In the App component we passed data property name to the Welcome component using name prop.

Now if we click on Change name button the name is property is updated so that the Welcome component prop is also updated with the new value.

Have you observed one thing the data property of an App component will be the prop to the Welcome component?

Conclusion

  • Data is private to the components and we can access that data from other components with the help of props.
  • Data is mutable and props are read-only.