Prevent user input in Vue.js until the value has been modified

Need help handling initial input values:

<input type="text" v-model="name" ref="input" />
<button type="submit" :disabled="$refs.input.defaultValue == $refs.input.value">Submit</button>

Encountering an error with the disabled binding:

Cannot read property defaultValue of undefined
. Any suggestions on how to streamline this without overloading vm.data?

Answer №1

An error has occurred:

The property defaultValue cannot be read from undefined

This issue arises because the ref is not immediately available:

It's important to note that refs are created as a result of the render function, so you cannot access them during the initial rendering phase - they simply do not exist yet! The $refs object is also non-reactive, meaning it should not be used for data-binding in templates.

When you add the ref to the template of the button, it tries to use it too early.

To work around this issue, you can implement a simple conditional statement:

<button type="submit" :disabled="!$refs.input || $refs.input.defaultValue == $refs.input.value">Submit</button>

However, there's a catch.


The defaultValue may not hold the expected value

When utilizing v-model, the defaultValue will always be an empty string ("") because Vue initially renders the <input> with an empty value.

If you wish to use a variable in the disabled button as intended, my suggestion is to make use of a mounted() method to store the initial value and compare it within the button template rather than using defaultValue.

A demonstration is provided below.

new Vue({
  el: '#app',
  data: {
    name: 'Hello Vue.js!'
  },
  mounted() {
    this.$refs.input.dataset.defVal = this.$refs.input.value;
  }
})
<script src="https://unpkg.com/vue"></script>

<div id="app">
  <p>{{ name }}</p>
  <input type="text" v-model="name" ref="input" />
  <button type="submit" :disabled="!$refs.input || $refs.input.dataset.defVal == $refs.input.value">Submit</button>
</div>


Another Option: Embrace Vue's Approach Completely

If possible, fully leverage Vue's reactive nature rather than manipulating the DOM directly.

The solution involves creating another variable set in the mounted() method:

new Vue({
  el: '#app',
  data: {
    name: 'Hello Vue.js!',
    defaultName: null
  },
  mounted() {
    this.defaultName = this.name;
  }
})
<script src="https://unpkg.com/vue"></script>

<div id="app">
  <p>{{ name }}</p>
  <input type="text" v-model="name"/>
  <button type="submit" :disabled="name == defaultName">Submit</button>
</div>

Alternatively, if both name and defaultName can be set to the same initial value, the mounted() logic mentioned above would not be required.

Answer №2

If I were to approach this problem, I might opt for a more detailed solution rather than simply relying on a disabled flag. My strategy would involve utilizing the @click.prevent directive to trigger a submit event.

Additionally, I would create a dedicated method for submitting the form and implementing a check that verifies whether the input has been altered. The method would return false if no changes have been made.

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

Looping through an array of nested objects using Vue

I have encountered a challenge with accessing specific data within an array that I am iterating over. The array is structured as follows, using Vue.js: companies: [ name: "company1" id: 1 type: "finance" additionalData: "{& ...

How can I create spacing between squares in an HTML div element?

Currently, I am working on my project using Laravel 5. I retrieve some integer values from a database and use them to create square divs in HTML. Below is the current output of my work. https://i.stack.imgur.com/sy2ru.png You may notice that there is spa ...

What is the best method for testing different versions of the same module simultaneously?

My goal is to distribute a module across various component manager systems like npmjs and bower. I also want to provide downloadable builds in different styles such as AMD for requirejs, commonJS, and a global namespace version for browsers - all minified. ...

Troubleshooting issue with Vue3 - TS Custom State Management

Issue: I am facing a challenge in transferring data between two separate components - the main component and another component. Despite attempting to implement reactive State Management based on Vue documentation, the object's value remains unchanged ...

What is the alternative to $templateCache in Angular2 and how can CachedResourceLoader be utilized in its place?

While I have come across 2 similar questions on Stack Overflow and here, none of them seem to provide a solution. After delving into the Angular repository, I stumbled upon this issue where they inquire about an alternative for templateCache in Angular 2, ...

The componentDidUpdate method ensures equality between the previous and current states

Within a dashboard, the layout data for each module (utilizing react-grid-layout) is stored separately from the module data and both are saved in a database. The Dashboard component state holds the current module data and layout data. I'm attempting t ...

What is the best way to extract raw data from a kendo dataSource?

After fetching data for my Kendo grid from the backend and populating it in the alignedProcessesToRiskGridOptions, I noticed that while the data is displayed in the grid, I also need access to the raw data for additional logic. Is there a way to retrieve d ...

The action 'onDeleteClick' cannot be executed as the property is undefined

Why is the onDeleteClick function working on the first <div>, but returning undefined on the second one? I am able to access the reference of this, but when clicking, it shows "onDeleteClick of undefined". I am confused as to why the onDeleteClick f ...

Displaying only one modal at a time with Bootstrap 3

The code snippet below is used to trigger my newsletter modal: $(window).load(function(){ if (sessionStorage.getItem("is_seen") === null) { setTimeout(function(){ $('#newsletter_modal').modal('show&ap ...

Error in scrolling previews detected in Jssor horizontal template maker

I've been working with Jssor Slider Maker and I'm using the vertical preview template that features two columns on the left side and a maximized image on the right side. After pulling the code from the developers pack, it includes scripts, CSS an ...

Verify user access rights with Vue.js Laravel

I am currently working on a project using Laravel and Vue. In my middleware, I have the following code: public function handle($request, Closure $next) { $user = auth()->user(); if ($user->hasRole('admin')) { return ...

How is Vue able to update the parent value from a child component without having to emit an event?

As a newcomer to Vue, I can't help but feel that this behavior goes against the principle of props down, events up. To counteract it, I've had success using Object.assign({}, this.test_object); when setting the value in the child-component. Shou ...

A guide to resolving the issue of invalid objects as a React child in Nextjs13

Seeking help on resolving an issue in Nextjs13, where I'm encountering the error "objects are not valid as a React child (found: [object Promise]). If you meant to render a collection of children, use an array instead" The scenario involves fetching ...

The paths generated by running npm build are incorrect

After building my Vue Cli 3 project using 'npm run build', I noticed that the 'index.html' file within the new 'dist/' folder has incorrect paths, such as: <link href=/css/app.35dee36a.css <link href=/js/app.826dde09.js ...

Error: Attempting to access the 'getProvider' property of an undefined variable

I am encountering an error that says "property of undefined (reading getProvider)" while deploying my function to Firebase. I am currently trying to figure out how to obtain the auth instance. When I attempt to use firebase.auth, it results in another er ...

Unable to load JQuery from a div element

My goal is to create a standard .html file containing the navigation, footer, and other elements that will be used across multiple pages for a small site I'm building. I want to keep it simple and avoid using php or other programming languages. I&apo ...

What is the best way to output information to a webpage using json_encode in PHP?

I've implemented a button on my webpage that triggers a database call using ajax, so the page can dynamically display the data without requiring a refresh. Oddly, when I click the button and inspect the source and network tab, everything seems to be f ...

Acquire a Vue component on a separate page by clicking a button on another Vue component or an HTML button click

Is there a way to dynamically load a Vue component on a different page when an HTML button is clicked? -HTML button <a class="contentButton ml-n5" id="addCategoryPrice">Add Price<i class="fa fa-plus-circle"></i ...

Why are two vertical scrolls appearing on the screen simultaneously?

I utilized this method to hide the body scrollbar initially and then display it upon clicking a link: $('body').css('overflow', 'hidden'); $('#site').click(function(e) { $('#wrapper').remove(); $(& ...

Toggle button color on click by using ng-click on a different button

As a newcomer to Angular, I am facing an issue. I have two buttons - button1 and button2. What I want is that when I click on button1, its color changes from green to red. Then, when I click on button2, the color of button1 should revert back to green. How ...