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rjsx-mode: A major mode for editing JSX files

MELPA Build Status

This mode derives from js2-mode, extending its parser to support JSX syntax according to the official spec. This means you get all of the js2 features plus proper syntax checking and highlighting of JSX code blocks.

Here's a screenshot of it in action:

Actual syntax highlighting and no spurious errors!

Installing

rjsx-mode is available on Melpa, so if you have that repository configured you can just package-list-packages and install it from there. (If not, you can follow their guide on getting started). rjsx-mode automatically registers itself for *.jsx files, but you can use (add-to-list 'auto-mode-alist '("components\\/.*\\.js\\'" . rjsx-mode))

Alternatively, you can download rjsx-mode.el from this repository and use load-file or similar to add it to your current session.

Features

js2-mode does not include a JSX parser, but rather an E4X parser, which means it gets confused with certain JSX constructs. This mode extends the `js2** parser to support all JSX constructs and proper syntax highlighting and indentation.

rjsx-mode adds some electricity to < and C-d to make adding new JSX elements less repetitive:

  • < inserts </> whenever it would start a new JSX node (and simply inserts < otherwise)
  • > or C-d right before the slash in a self-closing tag automatically inserts a closing tag and places point inside the element

The result is you can do the following:

Quickly and easily add new components

  • C-c C-r lets you rename the enclosing tag

Some features that this mode adds to js2:

  • Proper indentation of JSX regardless of how you write it. (No need to wrap in parentheses!)
  • Highlighting JSX tag names and attributes (using the rjsx-tag and rjsx-attr faces)
  • Parsing the spread operator {...otherProps}
  • && and || in child expressions <div>{cond && <BigComponent/>}</div>
  • Ternary expressions <div>{toggle ? <ToggleOn /> : <ToggleOff />}</div>

If you don't like this behavior, you can disable it by adding the following to your init file:

(with-eval-after-load 'rjsx-mode
  (define-key rjsx-mode-map "<" nil)
  (define-key rjsx-mode-map (kbd "C-d") nil)
  (define-key rjsx-mode-map ">" nil))

Additionally, since rjsx-mode extends the js2 AST, utilities using the parse tree gain access to the JSX structure.

Indentation

rjsx-mode extends the built-in javascript indentation engine to correctly support JSX. You can configue the depth of indentation using js-indent-level and sgml-basic-offset, along with the various js-indent- variables.

Indenting with tabs: This is not currently supported. You can either submit a PR if interested (look at issue #85) or revert to using the built-in indentation mode by adding (setq-local indent-line-function 'js-jsx-indent-line) to your rjsx-mode-hook.

Bugs, contributing

Please submit any bugs or feature requests on the GitHub tracker. Since this mode is based on js2, it is possible that bugs you encounter with it stem from there. Please try reproducing bugs using js2-mode if relevant. If the bug is in js2, please report it using M-x report-emacs-bug.

License

This project is licensed under the MIT license.

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