Javascript exception occurred

[elodd]

ReCaptchaDomain is http://localhost/, but at validate the webview is interrupted with a Javascript exception expecting ReCaptchaDomain in the html?

Unexpected Error: Error Domain=WKErrorDomain Code=4 \"A JavaScript exception occurred\"
UserInfo={WKJavaScriptExceptionLineNumber=24, WKJavaScriptExceptionMessage=TypeError:
Argument 1 (\'target\') to MutationObserver.observe must be an instance of Node,
WKJavaScriptExceptionColumnNumber=13, WKJavaScriptExceptionSourceURL=http://localhost/,
NSLocalizedDescription=A JavaScript exception occurred}"

[fjcaetano]

Hi @elodd, I just merged PR #68, which adds some documentation to README explaining that when generating your ReCaptcha key you must uncheck Verify the origin of reCAPTCHA solutions when using localhost as the domain.

Could you give that a go and let me know if it works?

[fjcaetano]

Hey @elodd, were you able to solve this? Is there anything we can do to improve the library?

[elodd]

Hi @fjcaetano,

No, unfortunately not, but minimised failure occasions by doing a redundant call for the setupReCaptcha functions when the above error occurs and maximised recapture security but always showing visual challenge.

When:

1. ReCaptchaKey is confirmed the same when registering and in the app.
2. ReCaptchaDomain is registered as localhost and http://localhost in the app.
3. Verify the origin of reCAPTCHA solutions is unchecked.

The above Javascript exception still occurs and breaks the flow.

[fjcaetano]

I'll investigate this further. I've just closed issue #70, which was a duplicate of this one.

The error there seemed to be because validate was being called too quickly, so it might be an issue with the logic that checks if all the JS resources were loaded.

A workaround was to add some delay before validating. Could you check if that minimizes the issue for you? Also, is this issue only happening in development (since you're using localhost) or in production also?

[elodd]

My understanding that since the token key is created on the mobile phone and not on a website or dns I need localhost for security reasons.

[fjcaetano]

@elodd you're free to use any domains you want, that's why the property is configurable. Did you try adding the delay I mentioned?

Using this library is a three-step process:

1. Load the library (by initializing it)
2. Configure the view (this may or may not be executed, depends on the JS code)
3. Validate the challenge

Ideally, you shouldn't try and execute all three at once. If that's what you're doing, you shouldn't run into any problems, but it's safer to add some time between them, specially loading and validating. Either way, any problems you may be encountering should be investigated.

[fjcaetano]

Are you by any chance using ReCaptcha v3? It looks like v3 is causing many issues with the library. If possible, please, try and use a v2 Invisible ReCaptcha key.

I'll look into adding support for v3 keys.

[elodd]

I used a v2 Invisible ReCaptcha key and a delay did not help.

[fjcaetano]

@elodd I was able to reproduce that issue by registering a wrong key or domain. Could you double check that on your side? Also, please check if you're using Google ReCaptcha's SITE KEY for the client side integration.

[elodd]

@fjcaetano Sorry I moved on working with a different project.