Is this the proper way to use the v-on:change directive?

Currently, I have set up a text input field with both a v-model and a v-on:change event attached to it. Whenever the user types something in the input field, an array in the data section gets updated and the UI is bound to that array. Additionally, I also want to trigger a method to send this user input data via AJAX. The data sent to the server is generated from a computed property.

<div id="app">
  <input
      id="user-input"
      type="text"
      v-model="userInput"
      v-on:change="process()">

   <ul id="parsed-list">
      <li v-for="item in parsedInput">
          {{ item }}
      </li>
    </ul>
</div>

let parse = (input) => {
    return input.split(',')
}

let serverProcess = (values) => {
    // Send array to server
}

new Vue({
  el: '#app',
  data: {
    userInput: ''
  },
  computed: {
    parsedInput () {
        return parse(this.userInput)
    }
  },
  methods: {
    process () {
        serverProcess(this.parsedInput);
    }
  }
});

I'm curious if it's considered best practice in Vue to use both v-model and v-on:change together in such scenarios?

Answer №1

If you're looking for a better approach than using v-on:change, I suggest utilizing a watch in Vue.js. By removing the v-on:change from the view, you can set up a watch function that will be triggered whenever the parsedInput property changes (which happens when the userInput changes). It's crucial to name the watch function the same as the computed or data property it's monitoring.

new Vue({
    computed: {
        parsedInput () {
            return parse(this.userInput)
        }
    },
    methods: {
        process () {
            serverProcess(this.parsedInput);
        }
    },
    watch: {
        parsedInput() {
            this.process()
        }
    }
})

For further information on watches in Vue.js, refer to https://v2.vuejs.org/v2/guide/computed.html#Watchers

In my opinion, this approach enhances the application's overall behavior through code rather than direct manipulation in the view. This not only improves testability but also ensures that the watch function will be invoked if changes occur in parsedInput or userInput outside the scope of v-model usage.

Answer №2

thumbs up @kmc0590000. Moreover, utilizing watch allows you to observe the previous state and current state by passing them as parameters.

v-model is essentially shorthand and performs the following:

<input :value="userInput" @input="change">

You can replace @change with v-on: and :value with v-bind:value.

In Line 6 (

v-on:change="process()"
), you have the option to omit the parentheses. The input event is passed to your method as a parameter, allowing you to directly access the attributes. (https://v2.vuejs.org/v2/guide/events.html#Method-Event-Handlers)

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