[prettierx] more flexible ternary conditional expression formatting

[brodycj]

updated:

Coming from multiple discussions including:

• Proposals for nested ternary formatting prettier/prettier#9561 - comparing proposals for nested ternary (conditional expression) formatting in upstream Pretter
• Use JSX style for all nested ternaries prettier/prettier#9552 - proposal to use the existing "JSX style" for all ternaries
• issue [prettierx] ternary formatting with objects & tabs needs improvement in upstream Prettier #552 - issue with nested ternary (conditional expression) formatting with objects & tabs
• issue known --offset-ternary-expressions formatting issues #468 - known nested ternary (conditional expression) formatting issues with --offset-ternary-expressions
• issue v0.20.0 with BREAKING CHANGES - ternary expressions formatting updates coming again #493 - upcoming 0.19.0 release, hopefully with a solution to known --offset-ternary-expressions formatting issues #468
• issue Inconsistent formatting of nested ternary expressions #41 - original issue with inconsistent formatting of nested ternary (conditional) expressions
• Various cases discussed in Incorrect indentation on ternary operator with object literal prettier/prettier#4203

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I would like to offer some more flexible ternary conditional expression formatting options for JavaScript, JSX, and other JavaScript-based languages.

I am thinking this should be configured through some options such as:

• --ternary-expression-formatting - choice of:
  • default - format like Prettier
  • balanced - same indenting for both the expression after ? and the expression after "
  • verbose - use the existing "JSX style" for all ternaries, as was proposed in Use JSX style for all nested ternaries prettier/prettier#9552
  • anything else?
• --jsx-ternary-expression-formatting - choice of:
  • default - "verbose" formatting like the upstream Prettier code
  • balanced - similar to "balanced" formatting above
  • anything else?
• --no-ternary-inner-indent - workaround for [prettierx] ternary formatting with objects & tabs needs improvement in upstream Prettier #552 (...) (I think we need something more flexible than a boolean config flag for the ternary indenting behavior)
• --inner-ternary-indenting - choice option with more flexible workaround for [prettierx] ternary formatting with objects & tabs needs improvement in upstream Prettier #552 ... should be able to add more choices in the future as needed - choice of:
  • default - same as upstream Prettier
  • ??? - ???
  • ??? - ???

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For upcoming 0.19.0 release (issue #493), I am thinking to just support options like these:

• --ternary-expression-formatting - choice of default | balanced
• --no-ternary-inner-indent - workaround for [prettierx] ternary formatting with objects & tabs needs improvement in upstream Prettier #552 (issue with nested ternary formatting with objects & tabs)
• --inner-ternary-indenting - choice of default | ???

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references:

• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator - documentation of conditional (ternary) operator in JavaScript
• https://www.c-sharpcorner.com/UploadFile/5089e0/ternary-conditional-operator-in-typescript/
• https://www.typescriptlang.org/docs/handbook/2/conditional-types.html
• https://skovy.dev/typescript-explained-in-javascript-conditional-types/