Debugging pack error - Githubissues

galan / packtag

A JSP Taglib for delivering minified, combined and gzip-compressed resources (JavaScript and CSS).

Apache License 2.0

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Debugging pack error #5

Closed dennis-johnson-dev closed 7 years ago

dennis-johnson-dev commented 9 years ago

I'm getting an "Uncaught SyntaxError: Unexpected identifier" in one my packs as I try and pack moment.min.js. Is there a way to debug or find out how to resolve this?

galan commented 9 years ago

Can you elaborate a bit? Which version of pack:tag do you use? Do you use special configuration? If so which Compressor for JS do you use? Did you tried to use the non-minimized version of moment.js, since compressing already manipulated JavaScript might have some issues.

dennis-johnson-dev commented 9 years ago

Sure, we have something like:

/bower/moment/2.9.0/min/moment.min.js

</pack:script> `

We're using Packtag version 3.11 and we tried the YUI compressor as well as the default. We also tried min/non-min moment.js. Firefox is saying that there is a missing ')' in an argument list. We also just learned that we get a similar error with immutable.js. Any ideas? Thanks.

pherris commented 9 years ago

I believe this is happening because the minified file we are trying to compress (with minify="false" in packtag) has a line length of 31,865 bytes which (I think) is longer than the default specified by Java's InputStreamReader which causes the file to be partially truncated. I see this in DisabledPackStrategy:

new InputStreamReader(resourceAsStream, charset);

where resourceAsStream is defined in PackTag.java as:

ByteArrayInputStream stream = new ByteArrayInputStream(minifedBuffer.toString().getBytes(UTF_8));

Also, I noticed that with minify set to false, the DisabledPackStrategy is used which extends the CssRewritePackStrategy (even though this is JS) - not sure if that is intended. I should mention that we are using the minify=false to only concatenate the pre minified files in an attempt to work around a different issue packing the non minified file.

galan commented 9 years ago

What I found so far:

Using an example-page which embedds moment-2.9.0.min.js fails with the missing ')'
Using an example-page which embedds moment-2.9.0.js fails with an error from JSMin due to an UnterminatedRegExpLiteralException
I created a dedicated test which just uses the PackStrategy or JSMin. On both JSMin packs the minified version (at least without exception), and fails with the UnterminatedRegExpLiteralException on the unminified version.
Testing on an independent online-resource, JSMin does not work on the non minified version either: http://compressorrater.thruhere.net/
Using js/moment-2.9.0.min.js/pack:script works

From what I can see, I think JSMin isn't able to minify the JavaScript resource. You might try a different PackStrategy, or use the minified version with the option minfy="false".

Thinking about the DisabledPackStrategy, I can't remember why it extends the CssRewritePackStrategy. I think it was for CSS resources, so relative paths inside are normalised. But I can't remember why I used it for JS.