The input value in the HTML form was altered momentarily before reverting back to its original state

Question

The input value in the HTML form was altered momentarily before reverting back to its original state

Researching this topic was quite challenging, but keep reading to find out why.

My objective is to detect any changes in a form field so that I can enable the "Save" button. While this seems easy enough, there's a catch. If the user reverts the input back to its original value when the form initially loaded, I want to disable the save button once again.

Here's a simple example:

Page loads - input displays "red"
User modifies it to "blue"

The script identifies the change from the original value and enables the save button

User then decides they preferred "red" and changes the input back to "red"

The script recognizes that the change is back to the original value and disables the save button

I understand that this may seem meticulous, but my clients fail to see the necessity of saving the form if the input returns to its initial state.

Naturally, this functionality needs to be applicable to multiple inputs on the form.

javascript jquery

Answer 1

Answer №1

It seems like you are utilizing an onChange callback that is linked to the 'change' event for input fields. To ensure that the save button is disabled when the value returns to its original state, you need a reference to the initial value.

The question arises about when you first determine the original value. Presumably, it is when you populate the input field with previously saved data, providing information about the "original" value.

To create specialized onChange callbacks for individual input fields, each with access to the original value, consider employing higher order functions. These functions can return new functions tailored to specific input elements.

function createOnChangeCallback(originalValue) {
   // returning a function!
   return function(changeEvent) {
      // this callback pertains to one input element, with access to "originalValue"
      const newValue = changeEvent.target.value;
      const hasGoneBackToOriginalValue = newValue == originalValue;
      if(hasGoneBackToOriginalValue) {
         // disable the submit button
      }
   }
};

When populating a particular field, follow steps like:

// obtain the input element's reference
const $myInput = $('#myInput');
// assign the initial value to the input field ("populate")
$myInput.val(originalValue);
// generate a specialized callback with access to the original value
$myInput.click( createOnChangeCallback(originalValue) )

Answer 2

It seems like you are utilizing an onChange callback that is linked to the 'change' event for input fields. To ensure that the save button is disabled when the value returns to its original state, you need a reference to the initial value.

The question arises about when you first determine the original value. Presumably, it is when you populate the input field with previously saved data, providing information about the "original" value.

To create specialized onChange callbacks for individual input fields, each with access to the original value, consider employing higher order functions. These functions can return new functions tailored to specific input elements.

function createOnChangeCallback(originalValue) {
   // returning a function!
   return function(changeEvent) {
      // this callback pertains to one input element, with access to "originalValue"
      const newValue = changeEvent.target.value;
      const hasGoneBackToOriginalValue = newValue == originalValue;
      if(hasGoneBackToOriginalValue) {
         // disable the submit button
      }
   }
};

When populating a particular field, follow steps like:

// obtain the input element's reference
const $myInput = $('#myInput');
// assign the initial value to the input field ("populate")
$myInput.val(originalValue);
// generate a specialized callback with access to the original value
$myInput.click( createOnChangeCallback(originalValue) )

Answer 3

Answer №2

Providing some additional context, the application is constructed using the .Net and MVC technology.

The main view page, where most of the action takes place, features a table displaying job request records. Each record includes an "Edit" link as shown:

<a href="/Job/_JobEdit?id=10079" class="btnJobEdit">Edit</a>

To handle events effectively due to dynamic loading and rendering of the table using DataTables.net, I utilize jquery at the document level.

In order to capture the "Click" event of the ".btnJobEdit" links and the "Change" and "Submit" events of the "#frmJobEdit", which only appears upon clicking the above "Edit" link, I employ the following approach.

$(document)
  .on('click', '.btnEditJob', event_click_btnEditJob)
  .on('change', '#frmJobEdit', function () {
    // leveraging jQuery validation library
    $(this).find(':submit').attr('disabled', !$(this).valid()); 
    $(this).find(':reset').attr('disabled', false);
  })
  .on('submit', '#frmJobEdit', event_submit_frmJobEdit)

With the initial page loaded successfully,

Upon clicking the "Edit" button for a record, the function event_click_btnEditJob() is executed.

Here's the breakdown of that straightforward function:

function event_click_btnEditJob() {
  event.preventDefault();

  $.get($(this).attr('href'), function (response) { 
    // expecting a full html form in response from the _JobEdit method of the JobController

    // Setting this into a BootStrap modal dialog and displaying it
    $('#modal_JobEdit .modal-body')
      .html(response)
      .modal('show') 
  }); 
}

When the user hits the "Save Changes" button, the function event_submit_frmJobEdit manages the submission through an ajax call to the JobController. This results in receiving another partial view with the updated data ready for editing again, along with an indication of the submit outcome - success or failure.

The current process is considered efficient, reliable, and straightforward. The introduction of the requirement to toggle the "Save" button based on user edits is seen as unfavorable from a development standpoint. As of now, the customer representatives involved in this project have reached a consensus: "Train the users!"

Answer 4

Providing some additional context, the application is constructed using the .Net and MVC technology.

The main view page, where most of the action takes place, features a table displaying job request records. Each record includes an "Edit" link as shown:

<a href="/Job/_JobEdit?id=10079" class="btnJobEdit">Edit</a>

To handle events effectively due to dynamic loading and rendering of the table using DataTables.net, I utilize jquery at the document level.

In order to capture the "Click" event of the ".btnJobEdit" links and the "Change" and "Submit" events of the "#frmJobEdit", which only appears upon clicking the above "Edit" link, I employ the following approach.

$(document)
  .on('click', '.btnEditJob', event_click_btnEditJob)
  .on('change', '#frmJobEdit', function () {
    // leveraging jQuery validation library
    $(this).find(':submit').attr('disabled', !$(this).valid()); 
    $(this).find(':reset').attr('disabled', false);
  })
  .on('submit', '#frmJobEdit', event_submit_frmJobEdit)

With the initial page loaded successfully,

Upon clicking the "Edit" button for a record, the function event_click_btnEditJob() is executed.

Here's the breakdown of that straightforward function:

function event_click_btnEditJob() {
  event.preventDefault();

  $.get($(this).attr('href'), function (response) { 
    // expecting a full html form in response from the _JobEdit method of the JobController

    // Setting this into a BootStrap modal dialog and displaying it
    $('#modal_JobEdit .modal-body')
      .html(response)
      .modal('show') 
  }); 
}

When the user hits the "Save Changes" button, the function event_submit_frmJobEdit manages the submission through an ajax call to the JobController. This results in receiving another partial view with the updated data ready for editing again, along with an indication of the submit outcome - success or failure.

The current process is considered efficient, reliable, and straightforward. The introduction of the requirement to toggle the "Save" button based on user edits is seen as unfavorable from a development standpoint. As of now, the customer representatives involved in this project have reached a consensus: "Train the users!"

Answer 5

Answer №3

Here's a suggestion:

$("#your-client-form").submit(function(e){
    e.preventDefault(); // This will stop the form from reloading the page.
});

Answer 6

Here's a suggestion:

$("#your-client-form").submit(function(e){
    e.preventDefault(); // This will stop the form from reloading the page.
});

Answer 7

Answer №4

Here is an illustration of a scenario similar to what you're aiming for.

// Example showcasing how to achieve the desired functionality
// data-field-name attribute specifies the JSON field name
const getFormData = () => {
  return $("#my-form");
};

const getFormStateData = (formData) => {
  let initialFormState = {};
  formData.children(":input").each(function() {
    const fieldName = $(this).data("fieldName");
    const fieldValue = $(this).val();
    if (fieldName) {
      initialFormState[fieldName] = fieldValue;
    }
  });
  return initialFormState;
};

const setSubmitButton = (formData, hasChanged) => {
  formData.children("#submit-form").prop("disabled", hasChanged);
};

const verifyAndUpdateFormState = (formData, initialFormState) => {
  const currentFormState = getFormStateData(formData);
  let hasChanged = false;
  for (const field of Object.keys(initialFormState)) {
    if (initialFormState[field] !== currentFormState[field]) {
      hasChanged = true;
      break;
    }
  }
  setSubmitButton(formData, hasChanged);
};

const attachListenersToFormFields = (formData, initialFormState) => {
  formData.children(":input").each(function() {
    if ($(this).data("fieldName")) {
      $(this).change(function() {
        const fieldName = $(this).data("fieldName");
        const fieldValue = $(this).val();
        verifyAndUpdateFormState(getFormData(), initialFormState);
      });
    }
  });
};

$(document).ready(function() {
  const formData = getFormData();
  attachListenersToFormFields(formData, getFormStateData(formData));
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form id="my-form">
  <input id="name" data-field-name="name" type="text" value="John" />
  <input id="age" data-field-name="age" type="text" value="12" />
  <input id="submit-form" type="submit" />
</form>

Answer 8

Here is an illustration of a scenario similar to what you're aiming for.

// Example showcasing how to achieve the desired functionality
// data-field-name attribute specifies the JSON field name
const getFormData = () => {
  return $("#my-form");
};

const getFormStateData = (formData) => {
  let initialFormState = {};
  formData.children(":input").each(function() {
    const fieldName = $(this).data("fieldName");
    const fieldValue = $(this).val();
    if (fieldName) {
      initialFormState[fieldName] = fieldValue;
    }
  });
  return initialFormState;
};

const setSubmitButton = (formData, hasChanged) => {
  formData.children("#submit-form").prop("disabled", hasChanged);
};

const verifyAndUpdateFormState = (formData, initialFormState) => {
  const currentFormState = getFormStateData(formData);
  let hasChanged = false;
  for (const field of Object.keys(initialFormState)) {
    if (initialFormState[field] !== currentFormState[field]) {
      hasChanged = true;
      break;
    }
  }
  setSubmitButton(formData, hasChanged);
};

const attachListenersToFormFields = (formData, initialFormState) => {
  formData.children(":input").each(function() {
    if ($(this).data("fieldName")) {
      $(this).change(function() {
        const fieldName = $(this).data("fieldName");
        const fieldValue = $(this).val();
        verifyAndUpdateFormState(getFormData(), initialFormState);
      });
    }
  });
};

$(document).ready(function() {
  const formData = getFormData();
  attachListenersToFormFields(formData, getFormStateData(formData));
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form id="my-form">
  <input id="name" data-field-name="name" type="text" value="John" />
  <input id="age" data-field-name="age" type="text" value="12" />
  <input id="submit-form" type="submit" />
</form>

The input value in the HTML form was altered momentarily before reverting back to its original state

Answer №1

Answer №2

Answer №3

Answer №4

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