Hi everyone!
SUMMARY
=========
I'm facing a problem with Document.get().getElementById(String) (in
Java) and $doc.getElementById(String) (in JavaScript) returning nulls.
My design goal is to define a <div> element in the Java code and add
it to the document, so that I can then retrieve it in the JSNI method
and use JavaScript libraries to draw stuff within it.
DESCRIPTION
============
To make problem description simpler, here is my GWT code:
1 protected void draw() {
2 String id = "divId";
3 HTML divElement = new HTML("<div id=\'" + id + "\'>Hello World</
div>");
4 getChartPanel().add(divElement); //getChartPanel() returns a
Panel
5 Window.alert("The element ID is " + id);
6 Element element = Document.get().getElementById(id);
7 Window.alert("The GWT element ID is " + element.getId());
8 drawJS(id);
9 }
10
11 public static native void drawJS(String divID) /*-{
12 $wnd.alert("The JS element ID is " + divID);
13 var chartPanel1 = $doc.getElementById(divID);
14 $wnd.alert("The chart panel is " + chartPanel1);
15 var chartPanel2 = document.getElementById(divID);
16 $wnd.alert("The chart panel is " + chartPanel2);
17 chartPanel.innerHTML("Hello, World!");
18 }-*/;
When the draw() method is called I get the following:
i) Window on line 5 pops up with "The element ID is divId";
ii) Window on line 7 pops up with "The GWT element ID is null";
iii) Window on line 12 pops up with "The JS element ID is divId";
iv) Window on line 14 pops up with "The chart panel is null";
v) Window on line 16 pops up with "The chart panel is null"; and
vi) A JavaScriptException is raised in development mode at line 17:
-----------------------------------------------------------
09:50:16.235 [ERROR] [sensor_network] Uncaught exception escaped
com.google.gwt.core.client.JavaScriptException: (ReferenceError):
chartPanel is not defined
fileName: http://127.0.0.1:8888
lineNumber: 7
stack: ("divId")@http://127.0.0.1:8888:7
@:0
-----------------------------------------------------------
ANALYSIS
========
I inspected the Web page with FireBug and the <div> element with id =
"divId" DOES exist after it is added in the Java code. However,
neither the Java nor the JavaScript methods are able to retrieve it.
QUESTIONS
==========
i) What am I doing wrong and how do I fix it?
ii) Is there a better way to add a <div> element in Java and pass it
to a JavaScript method, so that the latter can use it to add stuff
(e.g., JavaScript-based charts) in it?
Thank you.
G.
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