Cocoa Swift: Error evaluateJavaScript Optional("A JavaScript exception occurred")

Question

I'm loading WKWebView with a webpage and I'm trying to execute javascrip:

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) { 
     webView.evaluateJavaScript("document.getElementById('someElement').innerText") { (result, error) in
        if error != nil {
            print(error?.localizedDescription ?? "")
        }
    }
}

But I'm getting this error:

po error
▿ Optional<Error>
  - some : Error Domain=WKErrorDomain Code=4 "A JavaScript exception occurred" UserInfo={WKJavaScriptExceptionLineNumber=1, WKJavaScriptExceptionMessage=TypeError: null is not an object (evaluating 'document.getElementById('someElement').innerText'), WKJavaScriptExceptionColumnNumber=39, WKJavaScriptExceptionSourceURL=https://somewebsite.com/, NSLocalizedDescription=A JavaScript exception occurred}

Why I'm getting this error?, any of you knows what I'm doing wrong or a way around this?

Could you please print just error and not error.localizedDescription? You are hiding detailed information from yourself! — Sulthan
– Sulthan, Commented Apr 22, 2019 at 16:05
@Sulthan I have updated the error. Please let me know if you need anything else — user2924482
– user2924482, Commented Apr 22, 2019 at 20:17
null is not an object is obvious. It means there is no element with the given identifier someElement (the method getElementById returns null). Make sure you have typed the identifier correctly and that it really exists in the document. — Sulthan
– Sulthan, Commented Apr 22, 2019 at 21:13

Rachit Agarwal · Accepted Answer · 2019-04-23 04:29:49Z

2

+25

document.getElementById() returns null if the element couldn't be found. So I think 'someElement' name is not present in the web page.

answered Apr 23, 2019 at 4:29

Rachit Agarwal

3762 silver badges10 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Cocoa Swift: Error evaluateJavaScript Optional("A JavaScript exception occurred")

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related