[SugarCube] Problem with programmatically changing the start page

Erik Temple

For my project, I need to be able to direct the reader to any passage from the initial URL, so I have implemented a URL query that sets the startPassage config setting, redirecting to the chosen passage. E.g., "index.html?nav=My%20Passage" would trigger a change in the

This seems to work fine, until you also disable history controls so that the reader cannot use the browser's back/forward buttons to navigate through the story history. At that point, if you open a second instance of the story in the same window using a different startpoint, then press the browser button to go back to the first instance, SugarCube/Twine can't cope, triggering an error an error on Object.History, e.g.:

[quote]Error: Uncaught TypeError: Cannot read property 'title' of undefined.

Stack Trace:
TypeError: Cannot read property 'title' of undefined
    at Object.History.restore (file://localhost/Twine/Tests/Test.html:82:7806)
    at Object.History.init (file://localhost/Twine/Tests/Test.html:82:2963)
    at HTMLDocument.<anonymous> (file://localhost/Twine/Tests/Test.html:81:17642)
    at j (file://localhost/Twine/Tests/Test.html:26:26676)
    at Object.k.fireWith [as resolveWith] (file://localhost/Twine/Tests/Test.html:26:27489)
    at Function.o.extend.ready (file://localhost/Twine/Tests/Test.html:26:29283)
    at HTMLDocument.I (file://localhost/Twine/Tests/Test.html:26:29453)

(For example, you might first navigate to Test.html, then add a new location to the URL, e.g. Test.html?nav=Later. If you then hit the browser back button, you will have confounded the application's expectations, generating the error/stacktrace shown above.)

The relevant code:

:: Configuration [script]
config.disableHistoryControls = true;
config.startPassage = "Start";

:: StoryInit
<<script>>
... code to read URL queries into the opts object...

if (opts.hasOwnProperty("nav")) {
SaveSystem.deleteAuto();
config.startPassage = opts["nav"];
}
<</script>>

I'm not sure whether what I'm encountering is a bug in SugarCube--I'm not sure that programmatically changing the config option is really supported. Any ideas on what I can do here? Could I search through the browser window's history and eliminate any reference to my Twine's base URL before the currently running instance--if so, is there a safe way to do that?

Thanks for any help/advice!

EDIT: I have a minimal example and can supply if needed.

TheMadExile

1. Test cases are always welcome.

2. I think I know what's probably going on.  I'll take a look at it.

Erik Temple

Thanks! HTML for test case is attached, Twee source (exported from Twine 1.4.2) below.

:: Start
This is a test.

[[Next]]


:: Next
Continuing on...

[[Onward!]]


:: Onward!
End of test.


:: StoryInit
<<set $urlopts to {}>>
<<script>>
state.active.variables.urlopts = parseQueryString( window.location.search.substring(1) );
var opts = state.active.variables.urlopts;
for (var key in opts) {
if ( opts.hasOwnProperty(key) ) {
state.active.variables.urlopts[key] = decodeURIComponent(opts[key]);
if (state.active.variables.hasOwnProperty(key)) {
state.active.variables[key] = state.active.variables.urlopts[key];
console.log("Setting variable $"+ key + " to " + state.active.variables.urlopts[key]);
}
}
}
if (opts.hasOwnProperty("nav")) {
SaveSystem.deleteAuto();
config.startPassage = opts["nav"];
}
<</script>>


:: Configuration [script]
config.disableHistoryControls = true;
config.startPassage = "Start";

window.parseQueryString = function( queryString ) {
var params = {}, queries, temp, i, l;

// Split into key/value pairs
queries = queryString.split("&amp;");

// Convert the array of strings into an object
for ( i = 0, l = queries.length; i < l; i++ ) {
temp = queries[i].split('=');
params[temp[0]] = temp[1];
}

return params;
};

TheMadExile

A PM you have.  Read it you should!

Erik Temple

Read it I have. Thanks!