Simple wordpress ajax query is not working

Question

Do you have any idea why this simple wp ajax query is not working? It always returns fail. Console -> https://pastebin.com/TABQCjXe

jQuery(document).ready(function($) {

// This does the ajax request
$.ajax({
    type: 'post',
    url: ajaxurl,
    data: {
        'action':'prefix_load_cat_posts'
    },
    success:function(data) {
        // This outputs the result of the ajax request
        console.log(data);
        $( ".prefix_load_cat_posts" ).append("success");
    },
    error: function(errorThrown){
        console.log(errorThrown);
        $( ".prefix_load_cat_posts" ).append("fail");
    }
});

});

PHP -> https://pastebin.com/g4QiWDky

Answer 1

The action should be load-filter instead of prefix_load_cat_posts. Seeing your PHP code, the prefix_load_cat_posts is actually the callback function name.

data: {
    'action':'load-filter'
},

Answer 2

Your action it's 'load_filter', Also you are must be localize ajaxurl use this function wp_localize_script

$.ajax({
        type: 'post',
        url: ajaxurl,
        data: {
            'action':'load-filter'
        },
        success:function(data) {
            // This outputs the result of the ajax request
            console.log(data);
            $( ".prefix_load_cat_posts" ).append("success");
        },
        error: function(errorThrown){
            console.log(errorThrown);
            $( ".prefix_load_cat_posts" ).append("fail");
        }
    });

Answer 3

There is another alternate option. I am agree with samuel but i am sharing one more option

add_action( 'wp_ajax_nopriv_prefix_load_cat_posts', 'prefix_load_cat_posts' );
add_action( 'wp_ajax_prefix_load_cat_posts', 'prefix_load_cat_posts' );