WKWebView web worker throws error "Dom Exception 18 returns an error."

Question

I am writing an app using PhoneGap. I want to use javascript Web Worker. It works fine on Android. It also works on iOS with UIWebView.

I would like to use WKWebView in iOS 9. I tried to read the .txt files in a local folder successfully using cordova-plugin-file.

I have used the following tutorial: https://www.scirra.com/blog/ashley/25/hacking-something-useful-out-of-wkwebview

But this did not solve it...

new Worker ('js/tested.js');
Dom Exception 18 returns an error.
new Worker ('www/js/tested.js');
Dom Exception 18 returns an error.

I tried to specify the full path to worker javascript file, but I get the same error:

new Worker (file_path+'js/tested.js');
Dom Exception 18 returns an error.

So how to create the worker?

Answer 1

It worked!

Web workers without a separate Javascript file?

        var worker_js = null;

        function fetchLocalFileViaCordova(filename, successCallback, errorCallback)
        {
            var path = cordova.file.applicationDirectory + "www/" + filename;

            window.resolveLocalFileSystemURL(path, function (entry)
            {
                entry.file(successCallback, errorCallback);
            }, errorCallback);
        };

        function fetchLocalFileViaCordovaAsText(filename, successCallback, errorCallback)
        {
            fetchLocalFileViaCordova(filename, function (file)
            {
                var reader = new FileReader();

                reader.onload = function (e)
                {
                    successCallback(e.target.result);
                };

                reader.onerror = errorCallback;
                reader.readAsText(file);

            }, errorCallback);
        };

        fetchLocalFileViaCordovaAsText("js/worker.js", function (js_script) { // Worker WKWebView
            worker_js = window.URL.createObjectURL(
                new Blob([js_script], { type: "text/javascript" })
            );
        });

        if (worker_js != null) {
            backgroundEngine = new Worker(worker_js);
        } else {
            backgroundEngine = new Worker("js/worker.js");
        }