Iterating Over Elements with jQuery and Vanilla JavaScript: A Practical Guide

Introduction

When building dynamic web applications, you often need to manipulate or evaluate multiple elements on a webpage. Whether using jQuery or plain JavaScript, iterating over elements sharing the same class is a common task. This tutorial explores how to loop through elements with the same class name using both jQuery and vanilla JavaScript, applying conditions, and performing actions.

Understanding Element Iteration

Element iteration involves traversing DOM elements that share a specific characteristic, such as a CSS class name. By iterating over these elements, you can apply logic conditionally or uniformly across all selected items.

Using jQuery for Element Iteration

jQuery simplifies element manipulation with its concise syntax and powerful methods. One of the fundamental operations in jQuery is using the .each() method to loop through a collection of matched elements.

Basic Syntax

Here’s how you can use jQuery to iterate over elements with the class testimonial:

$('.testimonial').each(function(index, element) {
    // Access each element and its index within this callback
});

• .testimonial: Selects all elements with the testimonial class.
• .each() method: Iterates through these selected elements.
  • index: The zero-based position of the current element in the set.
  • element (or this): Represents the DOM object at that index.

Applying Conditional Logic

You can embed conditional logic within your iteration to perform specific actions based on certain criteria:

$('.testimonial').each(function(index, element) {
    if ($(this).data('index') > 2) {
        $(element).html(`Testimonial ${index + 1} updated`);
    }
});

In this example:

• $(this) or element: Refers to the current DOM object.
• .data('index'): Retrieves a data attribute, allowing for conditional checks.

Iterating with Vanilla JavaScript

While jQuery is widely used for its simplicity, modern browsers offer robust vanilla JavaScript capabilities. You can achieve similar functionality without relying on external libraries.

Using querySelectorAll and forEach

const elements = document.querySelectorAll('.testimonial');
elements.forEach((element, index) => {
    // Access each element and its index within this callback
});

• document.querySelectorAll(): Fetches all matching elements as a NodeList.
• Array.from(elements) or [...elements]: Converts the NodeList to an array for easier iteration with forEach.
• .forEach() method: Loops over each element.

Handling Older Browsers

For older browsers that don’t support NodeList.prototype.forEach, you can use:

var testimonials = document.querySelectorAll('.testimonial');
Array.prototype.forEach.call(testimonials, function(element, index) {
    // Conditional logic here
});

This approach uses call to apply forEach from the Array prototype to a NodeList.

Conclusion

Whether using jQuery or vanilla JavaScript, iterating over elements with shared characteristics is a fundamental task in web development. Understanding both methods allows you to choose the best tool for your project’s requirements and browser compatibility needs. With this guide, you should be well-equipped to manipulate multiple DOM elements effectively, applying conditions and actions as needed.

Remember that while jQuery provides convenience, vanilla JavaScript offers performance benefits, especially in environments where minimalism is key. Choose the approach that aligns with your project goals and constraints.