Detailed explanation of methods functions commonly used when instantiating Vue objects

Vue is one of the most popular front-end frameworks in recent years. It provides a responsive programming method that allows developers to build complex single-page applications more easily. In Vue, we use the methods function to define the logic for handling user interaction. More details are covered below.

1. What is the methods function

methods is where methods are defined on the Vue instance. These methods are available on Vue instances and can be bound to events in Vue templates. For example, we can define a method in methods to handle click events:

new Vue({
  el: '#app',
  data() {
    return {
      message: 'Hello World!'
    }
  },
  methods: {
    showMessage() {
      alert(this.message)
    }
  }
})

It can be used in templates like this:

<div id="app">
  <button v-on:click="showMessage">Click me</button>
</div>

2. Several ways to define methods functions

1. Direct definition

We can use object literals to directly define the methods function:

new Vue({
  methods: {
    showMessage() {
      alert('Hello, Vue!')
    }
  }
})

2. Use the arrow function of es6 syntax

The arrow function is used in a more concise way, and there is no need to write the function keyword:

new Vue({
  methods: {
    showMessage: () => {
      alert('Hello, Vue!')
    }
  }
})

3. Use the bind method to bind this

The bind method can bind the function Binds to the specified this value. In Vue, we usually bind this to the Vue instance so that we can access the data and methods on the Vue instance:

new Vue({
  methods: {
    showMessage: function() {
      alert(this.message)
    }
  }
}).$mount('#app')

// 模板中的绑定事件
<button @click="showMessage.bind(this)">Show message</button>

4. Use async/await

If you use async/await, you can also use them in methods to handle asynchronous operations:

new Vue({
  methods: {
    async fetchData() {
      const response = await fetch('/api/data')
      const data = await response.json()
      console.log(data)
    }
  }
})

3. Tips for using methods functions

1. Pass parameters

Sometimes we need to pass some parameters in the click event. In Vue, we can use the v-bind directive to pass parameters:

<div id="app">
  <button v-on:click="showMessage('Hello world')">Click me</button>
</div>

// Vue实例中定义方法
new Vue({
  methods: {
    showMessage(msg) {
      alert(msg)
    }
  }
})

2. Access Vue instance properties

We can access the properties on the Vue instance in the methods function , such as data attributes and computed attributes:

new Vue({
  data() {
    return {
      message: 'Hello World!'
    }
  },
  computed: {
    reversedMessage() {
      return this.message.split('').reverse().join('')
    }
  },
  methods: {
    showMessage() {
      alert(this.message + ' ' + this.reversedMessage)
    }
  }
})

3. Reuse the methods function

If we need to use the same method in multiple Vue instances, we can use the method Defined as global:

// 定义全局方法
Vue.prototype.$showMessage = function(msg) {
  alert(msg)
}

// 在Vue实例中使用
new Vue({
  methods: {
    showMessage() {
      this.$showMessage('Hello world!')
    }
  }
})

4. Summary

The methods function is a very important function in Vue, used to define the logic of processing user interaction. We can use object literals, arrow functions, bind methods and async/await to define methods functions. During use, we also need to understand methods such as passing parameters, accessing Vue instance properties, and reusing methods. These are all important means to improve development efficiency. I hope the introduction in this article can be helpful to everyone.

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