GWT-JSNI passes JavaScriptObject to external JS library
I am desesperatly trying to create an Anno object in a JSNI method, but I have a weird problem: the code in jsni method doesn't work, but if I do the same in my browser console, it works fine.
Java part
I am using JSONArray
which I am adding JSONObject
(with all items, according to Anno doc). Here's my JSNI method:
// I'm using the getJavaScriptObject() on my JSONArray
private static native void launch( JavaScriptObject steps )/*-{
var anno = new $wnd.Anno(steps);
anno.chainIndex().show();
}-*/;
Browser part
To be clear, the method is called on an event onShow
, so all ressources are loaded and displayed. So when the item is displayed and the function called, I have this error in my console:
Anno.target 'h1' could not be found. --- anno.js: 265
NB: In Anno.js, h1 is the dafault value for the target.
But my step values are correct and when I execute the same commands in the console, it works:
var testAnno = new Anno([{
content: "namespinnerFrequencyA",
position: "center-right",
target: ".dataAuto0"
},{
content: "chooseFrequencyB",
position: "top",
target: ".dataAuto1"}]);
testAnno.show();
I don't understand why it works in one case and not in another. I also tried to use JSON.stringify
then JSON.parse
, but it doesn't work either.
EDIT:
I understood something. While debugging anno.js, I figured out something: when I initialized Anno in the console, the local scope looks like this (larger image here ):
But when I use the jsni method the local scope is completely different, my parameter is stored as an actual array and not processed normally (larger image here ):
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The problem is that the GWT code is executed in an iframe (for sandboxed / sandboxed) and Anno only supports array types from the same view context .
See http://perfectionkills.com/instanceof-considered-harmful-or-how-to-write-a-robust-isarray/ and http://web.mit.edu/jwalden/www/isArray.html for a description Problems.
ECMAScript 5.1 added a feature Array.isArray()
that addresses this issue and has broad browser support (back to IE9): https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray And jQuery has one too, which makes it incomprehensible (to me) that Anno doesn't use it instead of using the broken one if arg.__proto__ is Array.prototype
(unless it's by design). So first things first: file an issue on Anno.
As a workaround, it should be possible to use $wnd.Array.apply($wnd.Array, steps)
to copy an array to an array from the top window.
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