How to fix "Uncaught SyntaxError: Unexptected token L in JSON at position 1"

Question

I have JavaScript function where a JSON parser is used:

function myFunction(jobj) {   
  jobj = JSON.parse(jobj);
  console.log("jobj: ", jobj);
}

I have 2 apps (one Visual Studio C# app and one Android Studio app) with a WebView "myWebView" where I call the JavaScript function "myFunction":

Code in C#

JObject jobj = new JObject();
jobj.Add("id", "testId");
jobj.Add("value", "1234");
String json = jobj.ToString(Newtonsoft.Json.Formatting.None, null);
String[]jsonArray = new String[] { json  };
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async () => await myWebView.InvokeScriptAsync("myFunction", jsonArray));

Code in Android:

JSONObject jsonObj = new JSONObject();
jsonObj.put("id", "testId");
jsonObj.put("value", "1234");
String json = jsonObj.toString();
String[]jsonArray = new String[] { json  };                                          
myWebView.loadUrl("javascript:myFunction('" + jsonArray + "')");

In C# it's working fine.

But in Android when I do the parse I get the error message:

Uncaught SyntaxError: Unexptected token L in JSON at position 1

Thanks, best regards Phil

Answer 1

In Android you're using Java. When you use the concatenation operator in Java, the operand is turned into a string. However, you are concatenating jsonArray, which is an array — and arrays' string representation is cryptic. For example, new String[] { "foo", "bar" }; stringifies as "[Ljava.lang.String;@2a139a55", not ["foo", "bar"] as it would in most sensible languages. You might replace jsonArray there with

"[" + String.join(", ", jsonArray) + "]"