Add function to every post?

One way to do that is to have the custom dropdown function return the custom html. Then you can call it inside your add_dropdown_to_posts and put the returned content into a helper variable. After that just prepend the custom html to the $content variable that the the_content filter provides.

Like this,

function my_custom_dropdown_html() {
 return '<html stuff here>'; // you could put your html also in a variable and then return that.
}
function add_dropdown_html_before_the_content($content) {
 $dropdown = my_custom_dropdown_html();
 // if statement just to be safe - e.g you change the custom function output to something else than string of html and forget you've used it here
 if ( $dropdown && is_string( $dropdown ) ) {
  $content = $dropdown . $content; // prepend custom html to content
 }
 return $content;
}
add_filter( 'the_content', 'add_dropdown_html_before_the_content' );

Related Posts:

  1. Import WordPress XML File from Within Functions.php
  2. Define custom Page Template without its own .php file
  3. Does hooking into the same action multiple times drain memory?
  4. How to influence the information displayed on widget inside wp-admin
  5. Extract image from content and set it as the featured image
  6. Is there a hook or function I can use to display all theme files being used on a current page?
  7. Issue with get_theme_mod returning a blank value instead of the saved value
  8. Show modified time if post is actually modified
  9. How to create thumbnails for PDF uploads?
  10. Implementing DNS Prefetching with WordPress
  11. Help me to understand wp_header() and wp_footer() functions
  12. How can I add an extra WooCommerce hook
  13. Remove Page Title from Static Frontpage
  14. How to override WordPress registration and insert an auto-generated username?
  15. Set default options for inserting media
  16. How to hook into the quick edit action?
  17. How do I change parameters without changing the core
  18. Is it possible to be more page/post specific with admin_enqueue_script?
  19. WooCommerce add_action hook results in 500 error
  20. Issue adding text after short description on product pages Woocommerce [closed]
  21. Customize “the_posts_pagination” and put list instead div
  22. Gravity Forms field entries into wp_query loop [closed]
  23. Post thumbnail relative link and HTML modify
  24. Accepted arguments value in hook functions
  25. Get current page_id before loop, in functions.php
  26. Which action hook to use for function?
  27. Change size and crop medium_large images
  28. Gravity Forms – Using a Form to Pre-populate A Gravity Form [closed]
  29. Running a script before absolutely everything
  30. Inserting a functions output after the content
  31. How to display post content instead of excerpt
  32. Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘greenday_head’ not found or invalid function name
  33. Modify a function without editing template
  34. Problem only while using require_once() within functions.php
  35. Passing values from a widget to a function within a plugin
  36. Which action does wp_update_user triggers?
  37. How can I get my Script to work on the Login page?
  38. Trigger a custom function when option are saved in admin area
  39. Execute a ultimate member action when user role is updated
  40. Add other social networks to TwentyNineteen_SVG_Icons class in child theme?
  41. How to use wp_trash_post (or wp_delete_post) for deleting a (or all) post(s) from custom post type?
  42. What did I do wrong in my functions code, that will not change the “Get New Password” text to “Send It”?
  43. Replace a menu with widget or a custom template file programmatically
  44. Registration Hooks don’t appear to be working
  45. jQuery does not work
  46. Pass parameter to hooked function using custom page template
  47. Override the WordPress core function wp_referer_field
  48. How to return hook data when multiple parameters are present?
  49. Hook into a function without a hook?
  50. Is my code correct to enqueue CSS on a specific page?
  51. Can’t properly set the_title add_filter to show short_URL
  52. Control the srcset much more (not all sizes in it each time)
  53. How to add_filter html template to middle of content
  54. Filter yoast canonical add_action priority [closed]
  55. (Woocommerce) Order by price when entering specific category
  56. How do I hook into the container of wp_nav_menu?
  57. Remove links from the_content when using filters wp_trim_excerpt
  58. Is there a way to prevent a function/method from being called outside a specific hook?
  59. Function not working inside of a function in functions.php
  60. Adding code before post title with the_title produces weird results
  61. Add back in child theme what the parent theme removed with remove_action
  62. Writing a function to detect an event
  63. This code works, but the way I integrated it is breaking the media uploader. How can I integrate it properly?
  64. Changing where my author box is printed
  65. Is it possible to use add_filter in an included file in the child theme’s functions.php?
  66. Insert Content Before div#main from the functions.php File
  67. Add Adsense code between job listings – wp job manager plugin
  68. update_post_meta is Updating with two page id
  69. Replace admin header logo with an image
  70. How to conditionally add a widget via a hook in functions.php
  71. How to place a div inside a function that creates a div
  72. Changing the text of Upload/Insert on Posts and Pages Screen
  73. How to add or delete default value theme options while activate and deactivate theme
  74. WordPress comment processing . Default unapproved comments detection before posting
  75. Warning at top of website & top menu gone
  76. Save_post – Warning: Cannot modify header information
  77. How to use WP conditional tag in a functions.php with OCEANWP Theme?
  78. custom error message for empty username and password using authenticate filter not working
  79. Get post_author email for Zapier Integration
  80. How can I stop the hook from breaking the login/logout function?
  81. True email confirmation for registration (keeping unvalidated users from user table)
  82. WordPress hooks to call a function inside a construct
  83. WordPress undefined function error on using add_action() in functions.php
  84. How to echo the translated custom field?
  85. Function the_content
  86. save_post hook – headers already sent?
  87. Init hook for header send
  88. Add custom fields after post/page title
  89. Force resize for all video content
  90. Unhook the comment form in Buddypress
  91. Why wp_ajax hooks doesn’t work?
  92. Why functions metaboxes is causing White Screen in Admin [closed]
  93. How do I add functionality to images?
  94. How to hook wp_mail to add a custom email as BCC for each sent email?
  95. image_size with respect to aspect ratios
  96. delete_term is not working properly with add_action()
  97. Get category of post inside save_post hook
  98. Create section wit form
  99. Log in and out using custom pages, no logout confirmation and redirects for logging in and out 2023
  100. Copy and Modified WooCommerce function is_coupon_valid [closed]
techhipbettruvabetnorabahisbahis forumutaraftarium24edueduseduedueduedueduedueduedu