Strange implicit camel-case conversion when use both unknown-options-as-args and alias

[weareoutman]

Given code below:

const result = require("yargs-parser")(
  ["--foo", "bar", "--outDir", "dist"],
  {
    string: ["_", "foo", "out-dir"],
    configuration: {
      "unknown-options-as-args": true 
    }
  }
);

console.log(result);

This will print:

{ _: [ '--outDir', 'dist' ], foo: 'bar' }

In which outDir is parsed as a positional argument. This makes sense because outDir is not presented in string, even though its kebab-case variation presented.

However, when I set an alias for out-dir, It behaves in another way:

const result = require("yargs-parser")(
  ["--foo", "bar", "--outDir", "dist"],
  {
    string: ["_", "foo", "out-dir"],
    configuration: {
      "unknown-options-as-args": true 
    },
    alias: {
      "o": "out-dir"
    }
  }
);

console.log(result);

This will print:

{ _: [], foo: 'bar', outDir: 'dist', o: 'dist', 'out-dir': 'dist' }

In which the former unknown option outDir is parsed as a named argument now. I don't know if there are some implicit conversions under the hood?

If the camel-case conversion is intended, I hope the first example will treat outDir as a known named argument too.

Tested in the current version of yargs-parser@20.2.6

[shadowspawn]

I found the underlying cause of the behaviour, but currently unsure whether can be untangled.

alias: gets extra processing compared with string:, and an implicit camelcase alias is added.

yargs-parser/lib/yargs-parser.ts

Lines 885 to 894 in 553c808

	flags.aliases[key] = ([] as string[]).concat(aliases[key] || [])
	// For "--option-name", also set argv.optionName
	flags.aliases[key].concat(key).forEach(function (x) {
	if (/-/.test(x) && configuration['camel-case-expansion']) {
	const c = camelCase(x)
	if (c !== key && flags.aliases[key].indexOf(c) === -1) {
	flags.aliases[key].push(c)
	newAliases[c] = true
	}
	}