Uglifyjs: Critical dependency: the request of a dependency is an expression

Created on 17 Jun 2017 · 8Comments · Source: mishoo/UglifyJS

this code:
https://github.com/mishoo/UglifyJS2/blob/master/tools/node.js#L18

will trigger a warning in webpack:

../~/uglify-js/tools/node.js
24:11-32 Critical dependency: the request of a dependency is an expression
    at RequireResolveContextDependency.getWarnings (/Users/others/wishlist/client/wishlist-client/node_modules/webpack/lib/dependencies/RequireResolveContextDependency.js:27:4)
    at Compilation.reportDependencyErrorsAndWarnings (/Users/others/wishlist/client/wishlist-client/node_modules/webpack/lib/Compilation.js:672:24)
    at Compilation.finish (/Users/others/wishlist/client/wishlist-client/node_modules/webpack/lib/Compilation.js:535:9)
    at /Users/others/wishlist/client/wishlist-client/node_modules/webpack/lib/Compiler.js:491:16
    at /Users/others/wishlist/client/wishlist-client/node_modules/webpack/node_modules/tapable/lib/Tapable.js:225:11
    at _addModuleChain (/Users/others/wishlist/client/wishlist-client/node_modules/webpack/lib/Compilation.js:481:11)
    at processModuleDependencies.err (/Users/others/wishlist/client/wishlist-client/node_modules/webpack/lib/Compilation.js:452:13)
    at _combinedTickCallback (internal/process/next_tick.js:95:7)
    at process._tickCallback (internal/process/next_tick.js:161:9)

The point here is that from that point webpack is unable to optimize the import and you endup with the whole js in your final bundle.

Source

rolele

Most helpful comment

I agree @alexlamsl.
Now we are talking about webpack which is one of the mainstream tool to build js today.
Look at what the core-team of webpack is saying about this issue here:
https://github.com/webpack/webpack/issues/196
This is a bad practice for the right reasons and can be easily solved in most cases (your case included)

rolele on 17 Jun 2017

👍4

All 8 comments

The point here is that from that point webpack is unable to optimize the import and you endup with the whole js in your final bundle.

That's by design.

kzc on 17 Jun 2017

I see that you import all the libs at that point.
Now what about the warning?

rolele on 17 Jun 2017

instead of the map function, you could just require each js and the warning will be gone.

rolele on 17 Jun 2017

If you need to parse & embed uglify-js, consider using the version generated by --self

alexlamsl on 17 Jun 2017

I need to see this warnig go away. that is all.
Instead of using the require function in your code passing a variable, you could simply:

    require.resolve("../lib/utils.js"),
    require.resolve("../lib/ast.js"),
   ...

rolele on 17 Jun 2017

@rolele thanks for the clarification, though I still don't see the point. We can't keep making cosmetic changes whenever a third party tool decides to emit a new warning.

alexlamsl on 17 Jun 2017

👍2