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Add Debugging guidelines [skip ci] #437
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CONTRIBUTING.md
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@@ -54,6 +54,31 @@ To run current plugin timing on a file: | |||
$ ./scripts/plugin-timing.js file.js | |||
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### Debugging | |||
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When you use babili in your project and you find that there is a bug that appeared ONLY when you used babili, it's most likely that there is a bug in Babili and you should definitely report it. Here are some guidelines that might help you drill down the issue. If it doesn't help you, you can of course create a minimal repro project with the bug and report it. |
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Consistent caps of Babili unless it's in quotes: babili
?
CONTRIBUTING.md
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2. The code is actually invalid syntax. | ||
3. You didn't turn on the relevant Babel plugin for that syntax (if experimental). | ||
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If the syntax error is at run time, then it means the outputted code is incorrect and and is a bug in the code generator, [babel-generator](https://github.com/babel/babel/tree/master/packages/babel-generator). |
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If the syntax error occurs at runtime, it likely means the code generator (babel-generator) has a bug and has output invalid code.
CONTRIBUTING.md
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2. Try to predict what caused the error and try relating it to some of the plugin names in the [packages/](packages) directory. The major ones (that do a lot of transformations) are - mangle, deadcode-elimination and simplify. | ||
3. Every plugin that Babili uses has an option in preset to toggle it on/off - [preset-options](packages/babel-preset-babili#options) | ||
4. Once you suspect a few transformations, try toggling that from the preset. As a good practice, if you think it's NOT a mangler bug, turn OFF mangling and you should see the unmangled variable names to debug easier. | ||
5. Sometimes it might NOT be a bug with one plugin but a combination of plugins. Again, deadcode and simplify are the major ones. You can start suspecting them first. |
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Again,
deadcode-elimination
andsimplify
may be good candidates to start with here as they perform many transformations.
CONTRIBUTING.md
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1. If there is an error in the console, as a first step, look around the code block where the error happens, and the code block of a few steps up in the stack. | ||
2. Try to predict what caused the error and try relating it to some of the plugin names in the [packages/](packages) directory. The major ones (that do a lot of transformations) are - mangle, deadcode-elimination and simplify. | ||
3. Every plugin that Babili uses has an option in preset to toggle it on/off - [preset-options](packages/babel-preset-babili#options) | ||
4. Once you suspect a few transformations, try toggling that from the preset. As a good practice, if you think it's NOT a mangler bug, turn OFF mangling and you should see the unmangled variable names to debug easier. |
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Maybe:
Disable any transformation(s) that you suspect are causing problems. Turning OFF mangling is a good practice if you don't think it's related to a mangling bug, since unmangled variable names will make debugging easier.
EDIT by @hzoo: Ref https://twitter.com/mikeal/status/833810594272731137