Vue.js - Disable submit button unless original form data has changed

Question

I have a simple form which I have created just for experiment purpose. I am trying to keep the button disable unless original form data is changed but still keep the button disabled if the data changes is reverted back to original data (undo).

<template lang="pug">
  form(@click.prevent="save")
    .main
      input(v-model="user.name")
      input(v-model="user.email")
      input(v-model="user.age")
      select(v-model="user.sex")
        option Male
        option Female
    .footer
      button(:disabled="isFormEnable") Save
</template>

<script>
export default {
  name: 'userForm',
  data () {
    return {
      user: {
        name: 'John Doe',
        email: 'john@gmail.com',
        age: '35',
        sex: 'Male',
      }
    }
  },

  computed: {
    isFormEnable () {
      // I am not sure what I need to do here but something like this may be:
      if (user.name) { return true }
    }
  },

  methods: {
    save () {
      console.log('Form Submitted')
    }
  }
}
</script>

I found a jQuery solution here but I am looking for vanilla/vue javascript solution.

$('form')
    .each(function(){
        $(this).data('serialized', $(this).serialize())
    })
    .on('change input', function(){
        $(this)             
            .find('input:submit, button:submit')
                .prop('disabled', $(this).serialize() == $(this).data('serialized'))
        ;
     })
    .find('input:submit, button:submit')
        .prop('disabled', true)
;

Instead of using computed, you can try using watched which watches properties change and reacts acc. to them — Meet Zaveri, Apr 03 '18 at 10:06

Jacob Goh · Accepted Answer · 2018-04-03T06:12:16.903

Here's how i would do it with the help of 1 module

npm i deep-diff

deep-diff is for comparing object values.

<script>
import { diff } from "deep-diff";

// default form value
const defaultUser = {
  name: "John Doe",
  email: "john@gmail.com",
  age: "35",
  sex: "Male"
};

export default {
  //...
  data() {
    return {
      user: { ...defaultUser } // cloning the object using object spread syntax
    };
  },

  computed: {
    isFormEnable() {
      // check if it's default value
      if (!diff(this.user, defaultUser)) return false;

      return true;
    }
  },
  //...
};
</script>

score 0 · Answer 2 · answered Jan 30 '21 at 08:07

Here's how to do it natively with Computed and Watch properties:

<template>
  <form>
    <label>Name</label>
    <input v-model='form.name' />

    <label>Age</label>
    <input v-model='form.age' />

    <button :disabled="!changed">Save</button>
  <form>
</template>

<script>
import _ from 'lodash'

export default {
  data() {
    return {
      changed: false, // for storing form change state
      form: {}, // data variable to store current form data binding
    }
  },

  computed: {
    // store the original form data
    originalForm() {
      return this.$store.state.form
    }
  },
  
  watch: {
    // by watching the original form data
    // create a clone of original form data
    // and assign it to the form data variable
    originalForm() {
      this.form = _.cloneDeep(this.originalForm)
    },

    // watch the changes on the form data variable
    form: {
      handler() {
        // using lodash to compare original form data and current form data
        this.changed = !_.isEqual(this.form, this.originalForm)
      },
      // useful to watch deeply nested properties on a data variable
      deep: true,
    },
  },

  created() {
    // dispatch an action to fill the store with data
    this.$store.dispatch('init')
  }
}
</script>

Checkout this blog for more details and better understanding.

Vue.js - Disable submit button unless original form data has changed

2 Answers2