New: Implements JSX syntax (fixes #18)

[JamesHenry]

@nzakas would be great to get your feedback on this!

Note: I added lodash.unescape as a dependency to ensure that HTML entities in JSX tags are decoded appropriately. Now that lodash is entirely modular, I felt that it was more prudent to include a micro-dependency than reinvent the wheel.

[eslintbot]

LGTM

[JamesHenry]

I have not had chance to report this one yet (jsx/multiple-blank-spaces), but might be another bug with some internal TypeScript utilities. The body of the AST is correct, but we cannot currently populate tokens array properly because of the issue.

[nzakas]

This looks really good. The only thing I think is missing is that it appears the parser will always parse JSX syntax. We may want to ensure that parse() only parses JSX when ecmaFeatures.jsx is true (as I'm sure there are people using TypeScript without JSX).

[JamesHenry]

Sorry if I am missing something obvious, but wouldn't the changes I made in parser.js (https://github.com/eslint/typescript-eslint-parser/pull/28/files#diff-09461573a85e2d94f056dd6814769042R112) achieve exactly that?

You can try creating and running an index.js in the root of the project with the following content as a quick POC:

var code = '<div>@test content</div>';
var parser = require('./parser').parse
console.log(parser(code, {ecmaFeatures: {jsx: true}}))

If ecmaFeatures.jsx is not truthy, it will throw.

Again, if I am missing something else, please let me know and I will fix it!

[nzakas]

All that ends up doing is changing the filename passed at https://github.com/eslint/typescript-eslint-parser/pull/28/files#diff-09461573a85e2d94f056dd6814769042R117

I'm not sure changing that filename is the same as enabling/disabling JSX support. Are you?

[JamesHenry]

But... https://github.com/eslint/typescript-eslint-parser/pull/28/files#diff-09461573a85e2d94f056dd6814769042R154? :)

As well using it to determine that filename, we are using extra.ecmaFeatures.jsx to inform the setting of the jsx option on the TypeScript compiler, and as we know from: https://github.com/Microsoft/TypeScript/wiki/JSX#basic-usage

In order to use JSX you must do two things.

• Name your files with the .tsx extension
• Enable the jsx option

...so that is both aspects covered, right?

[nzakas]

Oh, oops! Sorry, my Lyme brain must be getting to me. This looks good!

[nzakas]

I just pushed a new version with this fix.