Changes the add to cart text on woo commerce single products filtering by product category.

Change Woo Add to Cart Text

/*	CHANGE ADD TO CART BUTTON TEXT ON A PER PRODUCT BASIS
**********************************************************/


add_filter('single_add_to_cart_text', 'woo_custom_cart_button_text');
function woo_custom_cart_button_text() {

    if ( is_singular('product') ) {

        global $post;
        $donations_slug = 'donation';

        // get categories
        $terms = wp_get_post_terms( $post->ID, 'product_cat' );
        foreach ( $terms as $term ) $cats_array[] = $term->slug;

        if (in_array($donations_slug, $cats_array)) {
            return __('Donate Now', 'woocommerce');
        } else {
            return __('Add to Cart' , 'woocommerce');
        }
    }
}