Add ContainKeyAsync

src/Blazored.SessionStorage/ISessionStorageService.cs

@@ -11,6 +11,13 @@ public interface ISessionStorageService
 
         Task<string> KeyAsync(int index);
 
+        /// <summary>
+        /// Checks if the key exists in Session Storage but does not check the value.
+        /// </summary>
+        /// <param name="key">name of the key</param>
+        /// <returns>True if the key exist, false otherwise</returns>
+        Task<bool> ContainKeyAsync(string key);
+
         Task<int> LengthAsync();
 
         Task RemoveItemAsync(string key);

src/Blazored.SessionStorage/ISyncSessionStorageService.cs

@@ -10,6 +10,13 @@ public interface ISyncSessionStorageService
 
         string Key(int index);
 
+        /// <summary>
+        /// Checks if the key exists in Session Storage but does not check the value.
+        /// </summary>
+        /// <param name="key">name of the key</param>
+        /// <returns>True if the key exist, false otherwise</returns>
+        bool ContainKey(string key);
+
         int Length();
 
         void RemoveItem(string key);

src/Blazored.SessionStorage/SessionStorageService.cs

@@ -65,7 +65,9 @@ public async Task RemoveItemAsync(string key)
 
         public async Task<int> LengthAsync() => await _jSRuntime.InvokeAsync<int>("eval", "sessionStorage.length");
 
-        public async Task<string> KeyAsync(int index) => await _jSRuntime.InvokeAsync<string>("sessionStorage.key", index);
+        public async Task<string> KeyAsync(int index) => await _jSRuntime.InvokeAsync<string>("sessionStorage.key", index);
+        public async Task<bool> ContainKeyAsync(string key) => await _jSRuntime.InvokeAsync<bool>("sessionStorage.hasOwnProperty", key);
+
 
         public void SetItem<T>(string key, T data)
         {
@@ -136,7 +138,14 @@ public string Key(int index)
                 throw new InvalidOperationException("IJSInProcessRuntime not available");
 
             return _jSInProcessRuntime.Invoke<string>("sessionStorage.key", index);
-        }
+        }
+        public bool ContainKey(string key)
+        {
+            if (_jSInProcessRuntime == null)
+                throw new InvalidOperationException("IJSInProcessRuntime not available");
+
+            return _jSInProcessRuntime.Invoke<bool>("sessionStorage.hasOwnProperty", key);
+        }
 
         private async Task<ChangingEventArgs> RaiseOnChangingAsync(string key, object data)
         {