WP Rest Api / Ajax POST not working when not logged in

As stated in the documentation page you linked,

It is important to keep in mind that this authentication method relies on WordPress cookies. As a result this method is only applicable when the REST API is used inside of WordPress and the current user is logged in. In addition, the current user must have the appropriate capability to perform the action being performed.

Your JavaScript function is attempting to update a post – an interaction which affects the site’s database. Thus the REST API requires authentication in order to perform the operation. While REST authentication behaviors can be modified using the rest_authentication_errors filter, it’s highly inadvisable to disable authentication for the requests which require them by default, as doing so exposes your site to modification at virtually anyone’s whim.

You may wish to investigate alternate means of authentication, as alluded to in the documentation page you linked.

Related Posts:

  1. WP REST return value to error function from Request
  2. Display posts from another site using REST API in an asynchronous manner
  3. JSON parsing error syntax error unexpected end of input
  4. jQuery Ajax error handling, show custom exception messages
  5. My javascript is returning this error: $.ajax is not a function
  6. Ajax TypeError: $.POST is not a function
  7. TypeError: $.ajax(…) is not a function?
  8. XML Parsing Error: not well-formed in FireFox but good in Chrome
  9. How to get a cross-origin resource sharing (CORS) post request working
  10. jQuery Form Validation before Ajax submit
  11. jQuery – Illegal invocation
  12. jQuery ajax error function
  13. ajax stopped working when not logged in?
  14. Using jQuery to delete data stored in wp_options
  15. AJAX nonce with check_ajax_referer()
  16. wp_mail script with jQuery post
  17. Ajax call does not activate callback function
  18. AJAX call returns 0
  19. jQuery and AJAX Not working with Select Form Element
  20. How to pass both action and formdata in wordpress ajax?
  21. jquery & ajax getting data to php in wordpress
  22. AJAX returns response 0
  23. Basic WordPress AJAX Call
  24. AJAX post into pop-up div
  25. Bind to WPSetAsThumbnail
  26. Ajax not firing properly using Firefox, but works in Chrome
  27. Appending anchor tag to next post
  28. Registration e-mail check with AJAX
  29. Cannot access elements of json object
  30. Basic ajax call in WordPress
  31. Updating User Profile with AJAX not working
  32. Auto Load New Posts
  33. wp_ajax() question.. not using wp_enqueue_script?
  34. wp_ajax unauthenticated and authenticated
  35. Showing Author Information and Latest Post by author in lightbox when clicked on the name of the author
  36. WordPress ajax function parameter value not being passed
  37. Accept AJAX call with serialized form data
  38. How to add WP API and JS featured image attachment
  39. Is there a restriction in WP on the use of jQuery load function?
  40. Ajax not posting form data to query in PHP function
  41. Front-end Ajax File Upload
  42. Display data on same page as form without refresh
  43. gravity forms jQuery.load into modal [closed]
  44. Ajaxify calendar
  45. Error when posting comment form: The error is TypeError: e[h] is not a function
  46. jQuery ajax call throws an HTTP 302
  47. Ajax, Permalinks and post_thumbnail
  48. Accessing user Meta data via REST and backbone
  49. WooCommerce Ajax Cart Update Stopped Working
  50. WordPress AJAX Load More function duplicating a post
  51. Advanced Ajax Page Loader (AAPL) blocks resources
  52. First Attempt at AJAX and it keeps getting Canceled. Can’t Get Results to Show
  53. Passing a varible from jQuery to PHP
  54. videopress videos are not displayed when loading the content with ajax in a lightbox
  55. Retrieve post info within AJAX helper function
  56. How to return multiple arguments from AJAX callback function
  57. Why use admin-ajax.php when loading pages through AJAX?
  58. Why does my jQuery AJAX return 0?
  59. Simplest ajax form not working when it should
  60. how to json_encode(); the Loop content so that the encoded array is [“0”:content, “1”:content]
  61. Loading dynamic content with AJAX breaking jQuery
  62. why is my wordpress Jquery-Ajax call not working?
  63. How to retrieve WP_Object that is inside an array of another array
  64. fill form fields with ajax response
  65. Adding custom cart price with Ajax in wordpress
  66. Can’t add classes using jQuery from a JSON string with get_body_class()
  67. Ajax call through admin-ajax.php returns 404 error
  68. WordPress Insert not working with ajax
  69. Search query with Ajax
  70. WP AJAX API with JS file
  71. admin ajax php success returns 0
  72. Why is ajax working on one server and not the next?
  73. Is there some jQuery conflict here?
  74. How to use wp_update_post with ajax on frontend
  75. Getting jQuery AJAX to work in WordPress (getting -1)
  76. Connect Agile Carousel to WordPress AJAX
  77. Which hook to use when adding ajax to viewer-facing side?
  78. my example with ajax doesn’t work
  79. jQuery forms & updating info
  80. Loop through WordPress API response errors
  81. Orderby post__in Not Working Correctly?
  82. jQuery.post() calling function with parameter
  83. $_POST empty in using new php file added to theme
  84. Autocomplete for titles via ajax – rework of past post away from like_escape()
  85. Passing variable data from external jQuery file to options.php
  86. Retrieve customizer value using ajax or customizer api and print the value in theme
  87. Displaying contents of a tab
  88. owl carousel not working after ajax load [duplicate]
  89. WordPress version for this autocomplete jQuery code
  90. Ajax autocomplete based on usercode
  91. Variable not being returned from Ajax Javascript (though javascript receives it)
  92. jQuery AJAX add json2 dependency?
  93. How to respond with WP_Ajax_Response();
  94. How to pass more information though separate post keys via AJAX
  95. Loop not appending through infinite-scroll ajax call
  96. Get selected value with PHP and jQuery
  97. How to combine jQuery in-place editor with $wpdb->update
  98. Load loop images on click / defer image loading until click or other event
  99. Widget won’t work due to old JavaScript? Any ideas how to make it work? [closed]
  100. Custom WP rest api endpoint only working on non https?