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Duktape

This page contains notes about issues that came up while developing the Duktape Host.

This page is useful for tracking down errors. See Duktape Host for how to use the Duktape host.

Todo items

testCommon.js fails because of 'this'

Under Duktape and Node.js, testCommon.js fails because testSpontaneous.js has a missing this.. If Edward could take a look, that would be great.

The this issue is fixed. 4/15/2015

testCommon.js fails because of setInterval

In commonHost.js, line 495 is marked with --->:

• To even get this far, for some reason, it is necessary to have duktapeHost.js define copies of setInterval() etc. See below.

setInterval and setTimeout duplicate definitions

hosts/duktape/duktapeHost.js defines setInterval(), setTimeout() and clearInterval() even though they are defined hosts/duktape/duktape/examples/eventloop/ecma_eventloop.js.

We should be able to properly export these.

If duktapeHost.js has the definitions of clearInterval(), setInterval() and setTimeout() commented out, and these lines uncommented:

Then we don't get as far:

In common/commonHost.js, line number 1421 is marked with --->

So, it seems like if setTimeout() is defined in ecma_eventloop.js, then it is not available at this point?

Fixed!

The near term solution was to modify ecma_eventloop.js so that the declarations of setInterval etc. are in the global scope:

became

The same was done for clearTimeout(), setInterval() and clearInterval.

Also, the duk_cmdline.c was modified to invoke EventLoop.run() after the files were read.

The modSearch() definition is needed in each file to be loaded.

hosts/duktape/test/testCommon.js and hosts/duktape/test/testComposite.js both define modSearch(). Ideally, this would be built in.

Possibilities:

• Update or add a C definition of either require() or modSearch() to duktape.
• Or, have duktape read in a library definition file that defines this

In Progress The idea here is to use the Unix xxd utility to create a .h file that defines a string that is the contents of the duktapeHost.js file.

To do this, duktape/duktape/makefile was modified:

The top of the duktapeHost.h file looks like:

to get rid of compile-time warnings, remove the unsigned.

In duk_cmdline.c, before the Execute any argument file(s) comment, we load in the file:

Now, if hosts/duktape/test/testCommon.js contains:

and the following command is run from the hosts/ directory: duktape/duktape/duk duktape/test/testCommon.js, then the test runs!

Port modules to Duktape

We should start porting modules to Duktape.

Generate JUnit XML Output for the tests.

If we could generate JUnit-compatibile output from the Duktape tests, then we could include this in the nightly build.

This is lower priority, but it would be helpful

require() in Duktape

Duktape supports JavaScript require(), but a JavaScript method named modsearch() must be implemented.

The solution was to modify Duktape's examples/cmdline/duk_cmdline.c to load fileio_readfile() from examples/eventloop/fileio.c

Below is the patch to examples/cmdline/duk_cmdline.c, which is checked in to the accessors repo as accessors/web/hosts/duktape/duktape/examples/cmdline/duk_cmdline.c

In addition, examples/eventloop/fileio.c was updated to include better error checking

Also, Makefile.cmdline was updated to include examples/eventloop/fileio.c

All of the above changes were checked in to the Accessors repo.

The JavaScript side is based on code from http://wiki.duktape.org/HowtoModules.html

Below is the version in duktapeHost.js:

require(): cannot resolve module id

While in accessors/web/hosts/duktape, running

Results in

The error comes from duktape.c:

Adding the following to duktape.c and recompiling turns on debugging:

Rerunning the command produces a lot of debugging including:

  [DD] duk_bi_global.c:932 (duk__bi_global_resolve_module_id): resolve error: term was '..' but nothing to backtrack

which comes from

Solution: Running the command from the directory above and making the paths relative seems to help.

Loading util.js fails

Line 205 of commonHost.js is:

So, the issue here is that we don't have a util module.

The solution is covered in Require Discussion. Basically, under Duktape, we require ../common/modules/util.js.

cannot resolve module id: ../commonHost.js

After modifying duk_cmdline.c so that it loads in a C version of duktapeHost.js (see The modSearch() definition is needed in each file to be loaded.), then trying to load common/test/testCommon.js fails:

Enabling the debugging by editing duk_cmdline.c as per Compile with Debugging above results in

  [DD] duk_bi_global.c:932 (duk__bi_global_resolve_module_id): resolve error: term was '..' but nothing to backtrack

which is similar to require(): cannot resolve module id.

Because the output is so voluminous, I disabled the debug output.

One idea is to try running in different directories, such as the common/ directory

Editing Makefile.cmdline and setting CCOPTS to use -ggdb and not use -Os and then running under Mac OS X ggdb:

That's not much help, so instead, enabling the debugging by editing duk_cmdline.c as per Compile with Debugging above results in the following text after loading module: common/commonHost.js is echoed:

So, the problem here is that we have no error handler.

http://duktape.org/guide.html#error-handling is useful.

Solution: use duk_peval_string_noresult() in duk_cmdfile.c:

Now, we get a better error message:

The problem is that duktapeHost contains

when we run the duk command in the common/ directory, that won't work because from the common/ directory, there is no common/commonHost.js file.

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