Exploring the Best Practices of jQuery onchange Event Handling

In this jQuery tutorial, we will explore the jQuery change event with examples. We’ll discuss the jQuery change event, exploring its applications and covering different scenarios with use cases where it can be effectively employed.

What’s jQuery?

jQuery is a fast and lightweight open-source JavaScript library that allows developers to solve complex functionalities with simple code. It enables DOM manipulation, allowing users to find, select, and manipulate elements with specific properties. jQuery simplifies HTML Document Object Model (DOM) manipulation, Asynchronous JavaScript and XML (Ajax), and event handling.

Understanding the jQuery Change Event

The change event in jQuery is triggered when a user alters the value of an input, select, or textarea element.

The basic syntax for binding the change event is as follows:

$(document).ready(function() {
 $('selector').change(function() {
  // Your event handling logic here
 });
});

The 'selector' in jQuery can be an element ID, name, or class.

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Common Scenarios and Use Cases:

Form Validation

You can bind the change event to relevant form elements to trigger real-time validation and provide instant validation messages to users.

HTML Code:

<label for="myInput">Enter Username:</label>
<input type="text" id="myInput">

jQuery Code:

$(document).ready(function() {
     $('#myInput').on('change', function() {
    // Get the input value
    var inputValue = $(this).val();    // Perform validation
    if (validateInput(inputValue)) {
        // If validation passes, you can perform further actions
        console.log('Validation passed!');
    } else {
        // If validation fails, handle accordingly
        console.log('Validation failed!');
    }
  });
});

Dropdown change

You can bind the change event to a dropdown to update other parts of the page or other dropdown lists dynamically. You can dynamically update other parts of the page based on the user’s selection.

$(document).ready(function() {
 $('#dropdown').change(function() {
  loadSidebar($(this).val());
 });

 function loadSidebar(selectedValue) {
   console.log(selectedValue);
 }
});

In this scenario, the loadSidebar function is invoked whenever the user changes the selected option in the dropdown menu.

Checkbox and Radio Button Handling

You can use the change event for both checkboxes and radio buttons. Below is an example of handling the change event for checkboxes and radio buttons using jQuery:

Select checkbox Button:

$('input[type="checkbox"]').on('change', function() {
 var selectedCheckboxes = $('input[type="checkbox"]:checked');
 console.log(selectedCheckboxes);
});

The change event is used to detect when the checkbox is checked or unchecked. The :checked selector is employed to determine the checkbox’s state.

Select Radio Button:

$('input[type="radio"]').on('change', function() {
  var selectedRadio = $('input[type="radio"]:checked');
  console.log(selectedRadio);
});

The change event is used to detect when any radio button in the group is selected. The :checked selector is used to find the selected radio button, and its value.

Realtime Text Area Character Count

You can also bind the change event with a textarea to count the number of characters entered by the user in real-time.

$(document).ready(function() {
 $('#textarea').change(function() {
  countChar($(this).val().length);
 });

 function countChar(charCount) {
  console.log(charCount)
 }
});

Conclusion

We have explored the jQuery change event binding with elements. You can bind this event to input boxes, selects, etc. This is a powerful event for handling user input and applying appropriate actions.

To get started with jQuery, you can visit the official website: jQuery