What is the Composition API and how does it compare to the Options API?

Q: What is the Composition API and how does it compare to the Options API?

Learn the answer to "What is the Composition API and how does it compare to the Options API?" with detailed explanations, code examples, and best practices on DeployU.

The Scenario

You are a frontend engineer at a social media company. You are working on a new component that is very large and complex.

You are finding it difficult to organize the component’s code using the Options API, because the code for a single feature is spread out across multiple options (e.g., data, methods, computed).

The Challenge

Explain what the Composition API is in Vue and how it can be used to solve this problem. What are the key benefits of using the Composition API over the Options API?

Wrong Approach

A junior engineer might not be aware of the Composition API. They might try to solve this problem by breaking the component down into smaller components, which would be a good start, but it would not solve the underlying problem of code organization.

Addresses symptoms, not root cause

Right Approach

A senior engineer would know that the Composition API is the perfect tool for this job. They would be able to explain what the Composition API is and how to use it to organize the code for a large and complex component.

Step 1: Understand the Key Differences

Feature	Options API	Composition API
Organization	Code is organized by option (e.g., `data`, `methods`, `computed`).	Code is organized by logical concern (e.g., a feature).
Reusability	Code can be reused with mixins, but this can lead to name collisions and implicit dependencies.	Code can be reused with composable functions, which are more explicit and easier to reason about.
TypeScript	Limited TypeScript support.	Full TypeScript support.

Step 2: Choose the Right Tool for the Job

For our use case, we should use the Composition API. This is because we are working on a large and complex component, and the Composition API will allow us to organize the code by logical concern, which will make it more readable and maintainable.

Step 3: Code Examples

Here’s how we can rewrite our component using the Composition API:

Options API:

export default {
  data() {
    return {
      // ...
    };
  },
  methods: {
    // ...
  },
  computed: {
    // ...
  }
};

Composition API:

import { ref, computed } from 'vue';

export default {
  setup() {
    const myVar = ref(0);

    const myComputed = computed(() => {
      // ...
    });

    function myMethod() {
      // ...
    }

    return {
      myVar,
      myComputed,
      myMethod
    };
  }
};

As you can see, the Composition API allows us to group all the code for a single feature together in one place.

Systematic, production-ready debugging

Practice Question

You want to share a piece of reactive state between multiple components. Which of the following would be the most appropriate?

Questions