Vue.js 3.0 Tutorial

Vue.js 3.0 Component Advanced

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Vue.js 3.0 Reusable & Combinable

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Vue.js 3.0 Accessibility

Vue.js 3.0 Migrating from Vue2

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Vue.js 3.0 Style Guide

Vue 3.0 Style Guide

Introduction to Vue 3.0 Composition API

The Composition API is a set of additive, function-based APIs that allow flexible composition of component logic. It was introduced in Vue 3 as an alternative to the Options API to handle complex components and reuse functionality. Here's a basic step-by-step tutorial:

Installation:
Make sure Vue 3 is installed. If you haven't installed it yet, follow the instructions in the previous tutorial.
Creating a new component with Composition API:
Let's start with creating a new Vue component using the Composition API. Create a new file called MyComponent.vue in the components directory.
The template for MyComponent.vue could look like this:
```
<template>
  <button @click="incrementCount">Click me! You've clicked {{ count }} times.</button>
</template>
```
Importing and using reactive from Vue:
Below the template, let's add our script:
```
<script>
import { reactive } from 'vue';

export default {
  setup() {
    const state = reactive({
      count: 0
    });

    function incrementCount() {
      state.count++;
    }

    return { count: state.count, incrementCount };
  }
};
</script>
```
Here, we have used reactive to create a reactive state object. In the setup() function, we define all our reactive data and functions. Finally, we need to return anything that should be accessible in the template.

Using ref instead of reactive:

If you are handling simple variables like numbers, strings or booleans, you might want to use ref instead of reactive. Here's how to do it:

<script>
import { ref } from 'vue';

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

    function incrementCount() {
      count.value++;
    }

    return { count, incrementCount };
  }
};
</script>

Creating a reusable function:

If we have some logic that could be reused across several components, we can create a reusable function. Let's create useCounter.js:

import { ref } from 'vue';

export default function useCounter() {
  const count = ref(0);

  function incrementCount() {
    count.value++;
  }

  return { count, incrementCount };
}

Now, in our MyComponent.vue we can use this function:

<script>
import useCounter from './useCounter';

export default {
  setup() {
    const { count, incrementCount } = useCounter();

    return { count, incrementCount };
  }
};
</script>

This way, we've created reusable logic that can be imported into any component.

This is a basic overview of how the Composition API works in Vue 3. It allows you to have more control over your code and make it more maintainable and reusable.

Using Composition API for State Management in Vue 3.0:

Composition API facilitates state management by allowing the creation of reactive state variables using ref or reactive.

Example code:

<!-- StateManagement.vue -->
<template>
  <div>
    <p>{{ count }}</p>
    <button @click="increment">Increment</button>
  </div>
</template>

<script>
import { ref } from 'vue';

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

    const increment = () => {
      count.value++;
    };

    return { count, increment };
  },
};
</script>

Vue 3.0 Composition API and Reactivity:

Composition API leverages the reactivity system in Vue 3.0, making it easy to create reactive variables and track dependencies.
ref is used for creating reactive primitive values, and reactive is used for creating reactive objects.

Example code:

<!-- Reactivity.vue -->
<template>
  <div>
    <p>{{ message }}</p>
    <button @click="updateMessage">Update Message</button>
  </div>
</template>

<script>
import { ref } from 'vue';

export default {
  setup() {
    const message = ref('Hello, Vue!');

    const updateMessage = () => {
      message.value = 'Updated message';
    };

    return { message, updateMessage };
  },
};
</script>

Transitioning from Options API to Composition API in Vue 3.0:

Gradually transition by introducing composable functions alongside existing options-based code.
Use the setup function to set up the Composition API logic while keeping existing lifecycle hooks.

Example code:

<!-- TransitionExample.vue -->
<template>
  <div>
    <p>{{ message }}</p>
  </div>
</template>

<script>
import { ref, onMounted } from 'vue';

export default {
  data() {
    return {
      message: 'Hello, Vue!',
    };
  },
  setup() {
    const message = ref('');

    onMounted(() => {
      message.value = 'Updated message after mount';
    });

    return { message };
  },
};
</script>

Vue 3.0 Composition API and Code Organization:

Organize code by creating composable functions for specific features.
Use setup to call these functions and expose their results to the template.

Example code:

<!-- CodeOrganization.vue -->
<template>
  <div>
    <p>{{ formattedMessage }}</p>
  </div>
</template>

<script>
import { ref, computed, onMounted } from 'vue';

const useMessageFormatter = () => {
  const message = ref('Hello, Vue!');

  const formattedMessage = computed(() => message.value.toUpperCase());

  onMounted(() => {
    message.value = 'Updated message after mount';
  });

  return { formattedMessage };
};

export default {
  setup() {
    return useMessageFormatter();
  },
};
</script>

Vue 3.0 Composition API Examples:

Use Composition API for different features, such as fetching data, managing state, handling events, etc.

Example code:

<!-- CompositionAPIExamples.vue -->
<template>
  <div>
    <p>{{ formattedData }}</p>
    <button @click="fetchData">Fetch Data</button>
  </div>
</template>

<script>
import { ref, reactive, onMounted } from 'vue';

const useDataFetcher = () => {
  const data = reactive({ message: '' });

  const fetchData = async () => {
    const response = await fetch('https://api.example.com/data');
    data.message = await response.text();
  };

  return { data, fetchData };
};

export default {
  setup() {
    const { data, fetchData } = useDataFetcher();

    const formattedData = ref('');

    onMounted(() => {
      formattedData.value = data.message.toUpperCase();
    });

    return { formattedData, fetchData };
  },
};
</script>

Common Patterns with Vue 3.0 Composition API:

Common patterns include creating composable functions, using ref and reactive for reactivity, and leveraging lifecycle hooks within setup.

Example code:

<!-- CommonPatterns.vue -->
<template>
  <div>
    <p>{{ formattedData }}</p>
    <button @click="fetchAndFormatData">Fetch and Format Data</button>
  </div>
</template>

<script>
import { ref, onMounted } from 'vue';

const useDataFetcher = () => {
  const data = ref('');

  const fetchData = async () => {
    const response = await fetch('https://api.example.com/data');
    data.value = await response.text();
  };

  return { data, fetchData };
};

export default {
  setup() {
    const { data, fetchData } = useDataFetcher();

    const formattedData = ref('');

    const fetchAndFormatData = async () => {
      await fetchData();
      formattedData.value = data.value.toUpperCase();
    };

    onMounted(() => {
      fetchAndFormatData();
    });

    return { formattedData, fetchAndFormatData };
  },
};
</script>

Vue 3.0 Composition API and Component Logic:

Composition API allows for better organization and separation of component logic.
Composable functions can be created to encapsulate specific functionalities.

Example code:

<!-- ComponentLogic.vue -->
<template>
  <div>
    <p>{{ formattedMessage }}</p>
  </div>
</template>

<script>
import { ref, onMounted } from 'vue';

const useMessageFormatter = () => {
  const message = ref('Hello, Vue!');

  const formattedMessage = ref('');

  const formatMessage = () => {
    formattedMessage.value = message.value.toUpperCase();
  };

  onMounted(() => {
    formatMessage();
  });

  return { formattedMessage, formatMessage };
};

export default {
  setup() {
    const { formattedMessage, formatMessage } = useMessageFormatter();

    return { formattedMessage, formatMessage };
  },
};
</script>