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In Vue, sometimes we want to get the initial state of a data in data so that we can compare or reset it in subsequent operations. In this article, we will introduce how to get the initial state of a data in data and provide an example to illustrate the specific implementation of the process.

Get the initial state of a data in data

In Vue, we can get the current state of the data by referencing it, for example:

data() {
  return {
    message: 'Hello World'
  }
},
methods: {
  showMessage() {
    console.log(this.message);
  }
}

In the above code, we define a message variable and showMessagereference the message variable in the method. When the method is executed , the current value of messageshowMessage , 'Hello World', is output .

But if we want to get the initial state of the message variable, how should we do it? In Vue, we can use the created hook function to get the initial state of data in this function:

data() {
  return {
    message: 'Hello World'
  }
},
created() {
  console.log(this.message);
}

In the above code, we use the create hook function to get the initial state of the message and output it to the console. At this time, 'Hello World' will be output in the console.

Example

To better understand how to obtain the initial state of a certain data in data, we provide an example.

Suppose we have a form component with a form item called email. We hope to reset the form item after the user fills in the email to give the user the opportunity to fill in other information. To achieve this function, we need to get the initial value of email and reset email to its initial value after the user completes filling in and submits the form.

The following is sample code to implement this functionality:

<template>
  <div>
    <form @submit.prevent="submitForm">
      <label>
        Email:
        <input type="email" v-model="email" required>
      </label>
      <button type="submit">提交</button>
    </form>
  </div>
</template>

<script>
export default {
  data() {
    return {
      email: '',
      initialEmail: ''
    }
  },
  created() {
    this.initialEmail = this.email;
  },
  methods: {
    submitForm() {
      // process form logic
      // ...
      
      // reset email value
      this.email = this.initialEmail;
    }
  }
}
</script>

In the above code, we define a form component with an email form item. We use the v-model directive to perform two-way data binding on email. At the same time, we define a initialEmailvariable to save the initial value of email and assign the value of email to it in the createinitialEmail hook function .

When the user submits the form, we can call submitFormthe method to process the form logic. In this method, we reset the value of email to the value of initialEmail, thereby resetting the form item.

Summarize

Through the introduction of this article, we understand how to obtain the initial state of a certain data in data, and provide an example to explain in detail the implementation method of this process. In actual development, we can use this method according to specific circumstances to better meet our needs.