The difference between Vue3 and Vue2: lower learning curve

The difference between Vue3 and Vue2: lower learning curve

Vue.js is a popular JavaScript framework for building interactive user interfaces. Vue3 is the latest version of Vue.js, which introduces some major changes and optimizations to make learning and using Vue easier and more efficient. This article will introduce the main differences between Vue3 and Vue2, and illustrate these differences through some code examples.

1. Composition API

Vue3 introduces the Composition API, which is a new programming paradigm designed to provide better code organization and reuse. In contrast, Vue2 uses the Options API, which can lead to code that is too verbose and difficult to maintain when dealing with large components.

The following is an example of a component written using Vue2's Options API:

// Vue2 Options API
export default {
  data() {
    return {
      count: 0,
    };
  },

  methods: {
    increment() {
      this.count++;
    },
  },

  computed: {
    doubled() {
      return this.count * 2;
    },
  },

  created() {
    console.log('Component created');
  },
}

Using Vue3's Composition API, the above component can be rewritten as follows:

// Vue3 Composition API
import { reactive, computed, onMounted } from 'vue';

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

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

    const doubled = computed(() => {
      return state.count * 2;
    })

    onMounted(() => {
      console.log('Component created');
    });

    return {
      state,
      increment,
      doubled,
    }
  }
}

By comparing the two From the way of writing the API, it can be seen that the Composition API makes the component code clearer and neater. It allows us to organize related logic together and improve the readability and maintainability of the code.

2. Better type support

Vue3’s support for TypeScript is more complete. In Vue2, for projects using TypeScript, type checking needs to be implemented by declaring the type of a Vue instance. In Vue3, you can directly use the defineComponent function to define the type of the component, and use APIs such as ref and reactive in the component to achieve more precise type inference. .

The following is an example of a component using Vue2's Options API combined with TypeScript:

// Vue2 Options API with TypeScript
import Vue from 'vue';

export default Vue.extend({
  data() {
    return {
      count: 0,
    };
  },

  methods: {
    increment() {
      this.count++;
    },
  },

  computed: {
    doubled() {
      return this.count * 2;
    },
  },

  created() {
    console.log('Component created');
  },
});

In Vue3, you can directly use the defineComponent function to define the type of the component without Additional type declaration:

// Vue3 Composition API with TypeScript
import { defineComponent, ref, computed, onMounted } from 'vue';

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

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

    const doubled = computed(() => {
      return count.value * 2;
    })

    onMounted(() => {
      console.log('Component created');
    });

    return {
      count,
      increment,
      doubled,
    }
  }
});

It can be seen that Vue3 is more friendly to TypeScript support, helping developers improve the robustness and maintainability of the code.

3. Better performance optimization

Vue3 has made a series of optimizations in terms of rendering and update performance. The most important improvement is that the Proxy proxy object replaces Object.defineProperty in Vue2, which improves the performance of responsive systems. Vue3 also introduces static template compilation and optimized lazy loading mechanisms to further improve application performance.

The following is an example of a component written using Vue2 templates:

<template>
  <div>
    <p>{{ message }}</p>
    <button @click="changeMessage">Change Message</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      message: 'Hello, Vue!',
    };
  },

  methods: {
    changeMessage() {
      this.message = 'Hello, World!';
    },
  },
};
</script>

In Vue3, you can use the static template compilation function of the compiler to improve application performance:

<template>
  <div>
    <p>{{ message }}</p>
    <button @click="changeMessage">Change Message</button>
  </div>
</template>

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

export default {
  setup() {
    const state = reactive({
      message: 'Hello, Vue!',
    });

    const changeMessage = () => {
      state.message = 'Hello, World!';
    }

    return {
      ...state,
      changeMessage,
    }
  },
};
</script>

By using static template compilation and Proxy objects, Vue3 can render and update more efficiently, improving application performance.

Summary

Compared with Vue2, Vue3 introduces Composition API, improves type support and performance optimization, greatly reduces the learning curve and improves development efficiency. Through the comparison of code examples, we can see the improvements of Vue3 and encourage developers to upgrade to Vue3 as soon as possible to enjoy the benefits of the new version.

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