How to Add a Class to the ‘Add to Cart’ Button in WooCommerce

Description:
This guide explains how to add a custom CSS class to the “Add to Cart” button using a WordPress filter. Filters in WordPress allow you to modify or extend the behaviour of specific functions. Here, we’ll modify the classes applied to the “Add to Cart” button by hooking into the filter called cpb_add_to_cart_button_class.

What is the cpb_add_to_cart_button_class Filter?

The filter cpb_add_to_cart_button_class allows you to add, modify, or remove CSS classes from the “Add to Cart” button in WooCommerce. You can use this filter to apply custom styles by adding a new class to the button.

Parameters:

• $classes (array):
  This is the parameter passed to the filter. It contains an array of CSS classes that are applied to the “Add to Cart” button by default. You will add or modify these classes through your custom function.

Example of Usage:

Here’s a simple example of how you can add a custom class ('your-class') to the “Add to Cart” button using this filter.

Step 1: Define the Filter Callback Function

You first define a function that modifies the classes of the button. This function will be attached to the filter, allowing you to add new classes.

// Define a callback function for the filter.
function my_add_to_cart_button_class( $classes ) {
    // Add a new class to the array of classes.
    array_push( $classes, 'your-class' );   
    // Return the modified array of classes.
    return $classes; 
}

• Explanation:
  In this function, the $classes parameter is an array of classes applied to the “Add to Cart” button. The function is used array_push() to add a new class 'your-class' to this array. Finally, it returns the modified array of classes.

Step 2: Attach the Callback to the Filter

To apply your custom class to the button, you need to tell WordPress to use your callback function. This is done by attaching the function to the cpb_add_to_cart_button_class filter.

// Add the filter.
add_filter( 'cpb_add_to_cart_button_class', 'my_add_to_cart_button_class', 10, 1 );

• Explanation:
  The add_filter() function connects your custom callback to the cpb_add_to_cart_button_class filter. It tells WordPress, “Whenever this filter is triggered, run my function my_add_to_cart_button_class.”
  
• ‘cpb_add_to_cart_button_class’: The name of the filter you are modifying.
  
• ‘my_add_to_cart_button_class’: The function that will be executed when the filter is triggered.
  
• 10: The priority. A lower number means the function will run earlier.
  
• 1: The number of arguments that your callback function accepts (here, it’s just $classes).

Example of How the Filter Works:

Let’s say the default “Add to Cart” button has these classes:

<button class="button add_to_cart_button">Add to Cart</button>

After applying the filter and adding 'your-class', the button would look like this:

<button class="button add_to_cart_button your-class">Add to Cart</button>

Now, you can use CSS to style the button in a unique way:

.your-class {
    background-color: green;
    font-size: 18px;
    border-radius: 5px;
}

How to Remove the Filter

If you ever need to stop applying your custom class, you can remove the filter using the remove_filter() function.

// Remove the filter.
remove_filter( 'cpb_add_to_cart_button_class', 'my_add_to_cart_button_class', 10, 1 );

• Explanation:
  
  This tells WordPress to stop using the my_add_to_cart_button_class function with the cpb_add_to_cart_button_class filter. The parameters passed to remove_filter() must match those used in add_filter().

Where is the Filter Defined?

• File Location:
  
  The filter cpb_add_to_cart_button_class is located in the file:custom-product-boxes/public/cpb-template-functions.php
  
• Function Name:
  The function in which this filter is applied is called cpb_template_add_to_cart. This is likely the function that controls how the “Add to Cart” button is rendered for the Custom Product Boxes plugin.

Recap:

1. Define a Callback Function:
   
   Create a function that adds a new CSS class to the button’s classes array.
   
2. Attach the Function to the Filter:
   
   Use add_filter() to attach your function to the cpb_add_to_cart_button_class filter.
   
3. Remove the Filter (Optional):
   
   If needed, use remove_filter() to stop applying your custom class.

By following these steps, you can easily customize the “Add to Cart” button’s appearance in WooCommerce with your own CSS classes.