Make it possible to disable specific optimizations at will

[mathiasbynens]

It would be cool if there was an boolean option that we could pass to esmangle for each of these optimizations: https://github.com/Constellation/esmangle/blob/c9393254197119a73f92055ee6d1887535cbf47d/lib/esmangle.js#L254-L288

All the options would be true by default, but that way people could disable optimizations they don’t need/want, e.g.:

esmangle.optimize(ast, {
  'pass/hoist-variable-to-arguments': false
});

[michaelficarra]

The pipeline is the optional second parameter in optimize. mangle just does name mangling. See this example esmangle usage: https://github.com/Constellation/esmangle/blob/c9393254197119a73f92055ee6d1887535cbf47d/bin/esmangle.js#L66-L69

[mathiasbynens]

Thanks, @michaelficarra; I’ve edited my code example.

So far, I’ve only seen (and used) examples where null is passed as the second argument (= pipeline) to esmangle.optimize. What should pipeline look like if you only want to remove/avoid one or two optimizations?

[michaelficarra]

Yeah, unfortunately, it's a "replacement" API where, if you provide a value, it is used as an alternative to the default. If you want to disable just one transformation, you will have to explicitly specify all transformations except the one you'd like to omit. We could probably use an "except" style API.