How to overcome an HTMLUnit ScriptException?

Asked 1/12, 2013 at 17:57 Answered 14/11, 2022 at 11:5

I got a problem with a line of code that probably triggers some js function e couse an exception, how can i fix this?

box.setText(link.toString());
client.waitForBackgroundJavaScriptStartingBefore(10000);
box.dblClick(); //this line cause the exception

Exception in thread "main" ======= EXCEPTION START ========
EcmaError: lineNumber=[0] column=[0] lineSource=[function () {] name=[ReferenceError] sourceName=[onclick event for HtmlDivision[<div class="_119 stat_elem focus_target mtm mbl _5bsm _6dh _51z6" id="u_0_k" data-location="maincolumn" onclick="Bootloader.loadComponents(&quot;ComposerXControllerBootload&quot;, emptyFunction);">] in https://www.facebook.com/?_fb_noscript=1] message=[ReferenceError: "Bootloader" is not defined.]
com.gargoylesoftware.htmlunit.ScriptException: ReferenceError: "Bootloader" is not defined.
    at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine$HtmlUnitContextAction.run(JavaScriptEngine.java:684)
    at net.sourceforge.htmlunit.corejs.javascript.Context.call(Context.java:602)
    at net.sourceforge.htmlunit.corejs.javascript.ContextFactory.call(ContextFactory.java:507)
    at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine.callFunction(JavaScriptEngine.java:616)
    at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine.callFunction(JavaScriptEngine.java:591)
    at com.gargoylesoftware.htmlunit.html.HtmlPage.executeJavaScriptFunctionIfPossible(HtmlPage.java:985)
    at com.gargoylesoftware.htmlunit.javascript.host.EventListenersContainer.executeEventHandler(EventListenersContainer.java:210)
    at com.gargoylesoftware.htmlunit.javascript.host.EventListenersContainer.executeBubblingListeners(EventListenersContainer.java:230)
    at com.gargoylesoftware.htmlunit.javascript.host.Node.fireEvent(Node.java:804)
    at com.gargoylesoftware.htmlunit.javascript.host.Node.fireEvent(Node.java:738)
    at com.gargoylesoftware.htmlunit.html.HtmlElement$1.run(HtmlElement.java:869)
    at net.sourceforge.htmlunit.corejs.javascript.Context.call(Context.java:602)
    at net.sourceforge.htmlunit.corejs.javascript.ContextFactory.call(ContextFactory.java:507)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireEvent(HtmlElement.java:874)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.doClickFireClickEvent(HtmlElement.java:1311)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.click(HtmlElement.java:1253)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.click(HtmlElement.java:1205)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.dblClick(HtmlElement.java:1351)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.dblClick(HtmlElement.java:1326)
    at prototype.Profile.postLinkOnWall(Profile.java:225)
    at html.Log.findNext(Log.java:150)
    at prototype.Prtp.main(Prtp.java:49)
Caused by: net.sourceforge.htmlunit.corejs.javascript.EcmaError: ReferenceError: "Bootloader" is not defined.
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.constructError(ScriptRuntime.java:3603)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.constructError(ScriptRuntime.java:3587)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.notFoundError(ScriptRuntime.java:3657)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.nameOrFunction(ScriptRuntime.java:1749)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.name(ScriptRuntime.java:1690)
    at net.sourceforge.htmlunit.corejs.javascript.Interpreter.interpretLoop(Interpreter.java:1622)
    at net.sourceforge.htmlunit.corejs.javascript.Interpreter.interpret(Interpreter.java:798)
    at net.sourceforge.htmlunit.corejs.javascript.InterpretedFunction.call(InterpretedFunction.java:105)
    at net.sourceforge.htmlunit.corejs.javascript.ContextFactory.doTopCall(ContextFactory.java:405)
    at com.gargoylesoftware.htmlunit.javascript.HtmlUnitContextFactory.doTopCall(HtmlUnitContextFactory.java:309)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.doTopCall(ScriptRuntime.java:3031)
    at net.sourceforge.htmlunit.corejs.javascript.InterpretedFunction.call(InterpretedFunction.java:103)
    at com.gargoylesoftware.htmlunit.javascript.host.EventHandler.call(EventHandler.java:81)
    at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine$4.doRun(JavaScriptEngine.java:609)
    at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine$HtmlUnitContextAction.run(JavaScriptEngine.java:669)
    ... 21 more
Enclosed exception: 
net.sourceforge.htmlunit.corejs.javascript.EcmaError: ReferenceError: "Bootloader" is not defined.
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.constructError(ScriptRuntime.java:3603)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.constructError(ScriptRuntime.java:3587)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.notFoundError(ScriptRuntime.java:3657)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.nameOrFunction(ScriptRuntime.java:1749)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.name(ScriptRuntime.java:1690)
    at net.sourceforge.htmlunit.corejs.javascript.Interpreter.interpretLoop(Interpreter.java:1622)
    at script.onclick(onclick event for HtmlDivision[<div class="_119 stat_elem focus_target mtm mbl _5bsm _6dh _51z6" id="u_0_k" data-location="maincolumn" onclick="Bootloader.loadComponents(&quot;ComposerXControllerBootload&quot;, emptyFunction);">] in https://www.facebook.com/?_fb_noscript=1)
    at net.sourceforge.htmlunit.corejs.javascript.Interpreter.interpret(Interpreter.java:798)
    at net.sourceforge.htmlunit.corejs.javascript.InterpretedFunction.call(InterpretedFunction.java:105)
    at net.sourceforge.htmlunit.corejs.javascript.ContextFactory.doTopCall(ContextFactory.java:405)
    at com.gargoylesoftware.htmlunit.javascript.HtmlUnitContextFactory.doTopCall(HtmlUnitContextFactory.java:309)
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.doTopCall(ScriptRuntime.java:3031)
    at net.sourceforge.htmlunit.corejs.javascript.InterpretedFunction.call(InterpretedFunction.java:103)
    at com.gargoylesoftware.htmlunit.javascript.host.EventHandler.call(EventHandler.java:81)
    at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine$4.doRun(JavaScriptEngine.java:609)
    at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine$HtmlUnitContextAction.run(JavaScriptEngine.java:669)
    at net.sourceforge.htmlunit.corejs.javascript.Context.call(Context.java:602)
    at net.sourceforge.htmlunit.corejs.javascript.ContextFactory.call(ContextFactory.java:507)
    at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine.callFunction(JavaScriptEngine.java:616)
    at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine.callFunction(JavaScriptEngine.java:591)
    at com.gargoylesoftware.htmlunit.html.HtmlPage.executeJavaScriptFunctionIfPossible(HtmlPage.java:985)
    at com.gargoylesoftware.htmlunit.javascript.host.EventListenersContainer.executeEventHandler(EventListenersContainer.java:210)
    at com.gargoylesoftware.htmlunit.javascript.host.EventListenersContainer.executeBubblingListeners(EventListenersContainer.java:230)
    at com.gargoylesoftware.htmlunit.javascript.host.Node.fireEvent(Node.java:804)
    at com.gargoylesoftware.htmlunit.javascript.host.Node.fireEvent(Node.java:738)
    at com.gargoylesoftware.htmlunit.html.HtmlElement$1.run(HtmlElement.java:869)
    at net.sourceforge.htmlunit.corejs.javascript.Context.call(Context.java:602)
    at net.sourceforge.htmlunit.corejs.javascript.ContextFactory.call(ContextFactory.java:507)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireEvent(HtmlElement.java:874)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.doClickFireClickEvent(HtmlElement.java:1311)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.click(HtmlElement.java:1253)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.click(HtmlElement.java:1205)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.dblClick(HtmlElement.java:1351)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.dblClick(HtmlElement.java:1326)
    at prototype.Profile.postLinkOnWall(Profile.java:225)
    at html.Log.findNext(Log.java:150)
    at prototype.Prtp.main(Prtp.java:49)
== CALLING JAVASCRIPT ==
function () {
    [native code, arity=0]
}

======= EXCEPTION END ========

The box where I write, acts on a normal browser a reformatting function which is not performed using HtmlUnit so I tried to force it with a dbclick().

Veats answered 1/12, 2013 at 17:57 Comment(0)

HtmlUnit does not play well with JavaScript. It will frequently throw errors complaining about variables or functions not defined.

In that sense, real life browsers (FireFox, Internet Explorer, Chrome, etc) are much more flexible. That means that they will allow syntactically incorrect pieces of HTML and JavaScript (eg: not defining functions or not ending HTML tags).

HtmlUnit expects everything to be (almost) perfect. Although, it will fix some missing ending HTML tags, in general, it expects the code in the pages not to contain any kind of error. Furthermore, even if everything looks correct HtmlUnit might even complain.

Some items for you to think about are:

The most important one is switching between different BrowserVersions. You can set them when creating the WebClient object. Internet Explorer (ironically) has proven to give me the best results when it comes to interpreting JavaScript
Make sure your HTML and JavaScript code are both correct
Avoid using of complex libraries (jQuery seems to be properly supported)
Try to use non-minimized versions of libraries
If you happen to be using jQuery (or other similar libraries) avoid complex jQuery methods (eg: dynamically adding events to elements)

Of course, those comments would apply if you have control over the source code you're fetching from the server. Sometimes, this is not the case. In this situation your hands are even more tied.

One option, would be to suppress the exception with:

webClient.getOptions().setThrowExceptionOnScriptError(false);

Although, this will get you through the exception won't correct any JavaScript error. That means that if the JS piece of code that is throwing this exception happens to be crucial in your logic, I mean, you absolutely depend on the result of the execution of that code then you can not let HtmlUnit handle your JS. If this happens to be the result of an AJAX request then you can issue the request yourself manually instead of letting HtmlUnit do so.

On the other hand, if the JS code that is giving you trouble is not critical in your logic, I mean, it might just be hiding an element or changing a color that you don't care about, then suppressing the exception would be the way to go.

There aren't many options left.

Chronister answered 1/12, 2013 at 18:27 Comment(4)

I tried all the browsers, no one works. "Make sure your HTML and JavaScript code are both correct." how can i check this? – Veats 1/12, 2013 at 21:4

By properly programming the JS code (eg: not referencing uninitialised variable) and the markup (eg: closing all open tags or not using HTML 5 attributes in an HTML 4 document). Most likely the w3c validator will help you with the last one but I don't know any tool to validate JS code – Chronister 1/12, 2013 at 22:23

Alternative to use with Java? HtmlUnit has really been giving me a lot of problems. – Scholasticate 26/7, 2017 at 14:39

it doesn't work, I still have an exception: org.htmlunit.ScriptException: TypeError: redeclaration of variable i. even after adding webClient.getOptions().setThrowExceptionOnScriptError(false); – Degust 8/6 at 12:42

Try setting your web client not to throw exception:

client.getOptions().setThrowExceptionOnScriptError(false);

Mohun answered 1/12, 2013 at 18:4 Comment(2)

I'm trying to fix it more than escape the exception – Veats 1/12, 2013 at 18:14

it doesn't work, I still have an exception: org.htmlunit.ScriptException: TypeError: redeclaration of variable i. – Degust 8/6 at 12:42

I had this same problem when I get some website with method:

webClient.getPage("http://somepage.com");

If you don't need use JavaScript to working with websites you can write:

webClient.getOptions().setJavaScriptEnabled(false);

In my case it works well and script is performing immediately (when I used only webClient.getOptions().setThrowExceptionOnScriptError(false) then the script always tried perform bad JavaScript code and for about 10 seconds writing out exception messages in the console, so I don't recommend to use it).

Vinavinaceous answered 14/8, 2016 at 18:0 Comment(1)

you have disabled JS, not scripts were executed – Degust 8/6 at 12:41

Just to put additional salt into the wounds. HTMLUnit is pretty far behind when it comes to modern browser standards. Atm only a small subset of ES2015 is supported. The problem is that the underlying javascript engine (Rhino), has not moved forward fast enough. If you want to stay in the java realm for testing I would recommend to have a serious look at Selenium Webdrivers and use chrome in headless mode as engine. This is not a pure java solution anymore but uses the latest engine. Until HTMLUnit switches to a different engine, and/or Rhino get its act together HTML Unit definitely is not recommendable for javascript unit testing.

Niple answered 14/11, 2022 at 11:5 Comment(0)

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