onChange的shipment-price，您将有一个路由返回shipment value。

$(document).ready(function(){
        $('#shipment-price').on('change', function(e){ //on change of shipment-price 
        let shipmentValue = $('#shipment-price').val(); // the dropdown item selected value
        $.ajax({
            type : "GET",
            dataType : 'json', 
            url : "{{route('pricevalue', ['id'=>"+shipmentValue+"])}}",
            success : function(data){
                console.log(data);
                if(data.status){ //from your response 
                    $('#shipping-value').val(data.amount) // you can check the console to be sure of the response  
                }
            },error: function(e){
                console.log(e);
            },
        })
    });
})

您的路线将如下所示：

Route::get('/get-shipment-price/{id}', [ShipmentController::class, 'getShipmentPrice'])->name('pricevalue');

而YourController中的getShipmentPrice函数看起来像：

public function getShipmentPrice(Request $request)
    {
        $shipmentPrice = Shipment::where('shipment-type', $request->id)->first();
        if ($shipmentPrice) {
            return response()->json([
                'status' => true,  'data' => $shipmentPrice
            ]);
        }
        return response()->json([
            'status' => false, 'message' => 'Error',
        ]);
    }