MethodNotAllowedHttpException error in Laravel 5.7 using ajax [duplicate]

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Im trying to insert data with ajax, but i got error :

Symfony \ Component \ HttpKernel \ Exception \ MethodNotAllowedHttpException

This is my form in add-gallery.blade.php:

<form method="post" action="" enctype="multipart/form-data" autocomplete="off" class="mt-4 mb-4 card p-4">
      <div class="form-group">
        <div class="row">
          <div class="col-md-2 align-self-center">
            <label for="gallery_name">Name</label>
          </div>
          <div class="col-md-6 align-self-center">
            <input type="text" name="gallery_name" id="gallery_name" class="form-control" placeholder="Type Gallery Name" />
          </div>
        </div>                                    
      </div>
      <div class="form-group">
        <div class="row">
          <div class="col-md-2 align-self-center">
            <label for="category">Category</label>
          </div>
          <div class="col-md-3 align-self-center">
            <select class="form-control custom-select" name="category" id="category">
              <option value="">Select Category</option>
              <option value="Home">Home</option>
              <option value="Office">Office</option>
            </select>
          </div>
        </div>
      </div>
      <div class="form-group">
        <div class="row">
          <div class="col-md-2 align-self-center">
            <label for="subcategory">Sub Category</label>
          </div>
          <div class="col-md-3 align-self-center">
            <select class="form-control custom-select" name="subcategory" id="subcategory">
              <option value="">Select Sub Category</option>
              <option value="Interior">Interior</option>
              <option value="Eksterior">Eksterior</option>
              <option value="Decoration">Decoration</option>
            </select>
          </div>
        </div>
      </div>
      <div class="form-group">
        <div class="row">
          <div class="col-md-2 align-self-center">
            <label for="subsubcategory">Subsub Category</label>
          </div>
          <div class="col-md-3 align-self-center">
            <select class="form-control custom-select" name="subsubcategory" id="subsubcategory">
              <option value="">Select Subsub Category</option>
              <option value="Room">Room</option>
              <option value="Bathroom">Bathroom</option>
              <option value="Kitchen">Kitchen</option>
              <option value="Terrace">Terrace</option>
            </select>
          </div>
        </div>
      </div>
      <div class="form-group">
        <div class="row">
          <div class="col-md-2">
            <label for="gallery_image">Image</label>
          </div>
          <div class="col-md-10">
            <div class="fileinput fileinput-new" data-provides="fileinput">
                <div class="fileinput-new thumbnail w-100" style="display: none;">
                  <img src="http://placehold.it/1186x800" />
                </div>
                <div id="toAnnotate" class="fileinput-preview fileinput-exists thumbnail w-100"></div>
                <div>
                  <span class="btn btn-xs btn-success btn-file"><span class="fileinput-new">Select image</span><span class="fileinput-exists">Change</span><input type="file" name="gallery_image" id="gallery_image"></span>
                  <a href="#" class="btn btn-xs btn-danger fileinput-exists" data-dismiss="fileinput">Remove</a>
                </div>
            </div>
            <p><small><em>Image Size : 1186px (width), 800px (height)</em></small></p>
          </div>
        </div>
      </div>

      <div class="form-group">
        <div class="row">
          <div class="col-md-2 align-self-center">&nbsp;</div>
          <div class="col-md-10 align-self-center">
            <button type="button" class="btn btn-secondary">Cancel</button>
            <button type="submit" class="btn btn-success" id="save">Save</button>
          </div>
        </div>    
      </div>
    </form>

And below is my ajax in same page add-gallery.blade.php:

<script type="text/javascript">
  $(document).ready(function (e) {
    
    $.ajaxSetup({
      headers: {
        'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
      }
    }); 
    //Save
    $('#save').on('click', function () {
        var gallery_name    = $('#gallery_name').val();
        var category        = $('#category').val();
        var subcategory     = $('#subcategory').val();
        var subsubcategory  = $('#subsubcategory').val();
        var gallery_image   = $('#gallery_image').val();

        var dataSubmit      = $(this).serialize();        
        var top             = top;        
        var left            = left;

        var file_data = $('#gallery_image').prop('files')[0];
        var form_data = new FormData();
        form_data.append('file', file_data);
        
        $.ajax({
            url         : "",
            dataType    : 'text', // what to expect back from the server
            cache       : false,
            contentType : false,
            processData : false,
            data        : form_data,
            type        : 'post',
            dataType    : 'json', 
            success: function (response) {
              console.log(response);
            },
            error: function (response) {
              console.log(response);
            }
        });
    });
  });
</script>

This is my routes file web.php:

Route::post('galleries/store','Dashboard\GalleryController@store');

And this is my controller GalleryController.php:

    public function store(Request $request){
        if($request->hasFile('gallery_image')){ 
            $fileImage = $request->file('gallery_image'); 
            
            $fileImageExtension = $fileImage->extension(); 
            $renameFileImage    = 'ImageGalleries'.time().'.'.$fileImageExtension; 
            $pathFileImage      = $fileImage->storeAs('public/galleries_documents/images_galleries', $renameFileImage);  /images_articles

            
            $galleries              = new Gallery; 
            $points                 = new Point; 

            $galleries->name            = $request->gallery_name;
            $galleries->category        = $request->category;
            $galleries->sub_category    = $request->subcategory;
            $galleries->sub_subcategory = $request->subsubcategory;
            $galleries->image           = $renameFileImage;
            $galleries->lang_id         = session('lang_id');
            $galleries->save();

            $lastInsertId = $galleries->id;

            for($i = 0; $i < count($request->node); $i++) {
                $node[] = [
                    'node_position_top'     => $request->node[$i],
                    'node_position_left'    => $request->node[$i],
                    'id_gallery'            => $lastInsertId,
                ];
                
                $points->lang_id            = session('lang_id');
            }

            Point::insert($node); //save to table 

            print_r($node[]);

            exit();
        }
    }

via Chebli Mohamed