Language grammar for all versions of JavaScript including ES2016 and ESNext, JSX syntax as used by Facebook React, Atom's etch and others, as well as optional typed JavaScript using Facebook flow. The colour of syntax is determined by the theme in use.

The package also provides

• automatic indentation of JSX (optional).
• JSX tag closure and JSX html element completion suggestions.
• Context aware commenting out of JSX elements.
• Additional newline insertion between JSX tag pairs.
• Babel transpilation on file saves (optional).
• Babel transpile of all files in a directory or directories.
• Babel transpiled code preview.

By default the language-babel package will detect file types .js,.babel,.jsx, es, es6 and .flow. Use the standard ATOM interface to enable it for other file types. This provides a grammar that scopes the file in order to colour the text in a meaningful way. If other JavaScript grammars are enabled these may take precedence over language-babel. Look at the bottom right status bar indicator to determine the language grammar of a file being edited. language-babel will be shown as Babel ES6 JavaScript

language-babel provides Babel V6 & V5 transpiler support. If you only require grammar/syntax highlighting ensure that the package settings Transpile On Save and Allow Local Override are both off.

Install via ATOM or by using apm install language-babel. If you only need to use the provided grammar read no further!

JSX tag closures are provided as auto complete options. In addition common HTML elements and their associated properties are displayed as auto complete lists. Those supported by language-babel are described here

JSX elements cannot be commented out by using standard // or /* */ commenting. Normally {/* */} is used instead. language-babel changes the Atom toggle comments behaviour when inside a JSX block to support this behaviour. Nested elements within JSX that require a // form of commenting will be detected automatically.

When a newline is inserted between a matched open/close pair of JSX tags, language-babel inserts an additional line and positions the cursor. If Auto Indent is also turned on then the cursor is correctly indented.

By default this feature is turned off in the package setting - Auto Indent JSX. If enabled, language-babel will auto-indent any JSX code typed or moved across using suitable Atom defaults. There are also three commands - language-babel:toggle-auto-indent-jsx, language-babel:auto-indent-jsx-on and language-babel:auto-indent-jsx-off that override the default behaviour. These can be mapped to a keyboard shortcuts if needed.

Auto Indenting will also attempt to read the .eslintrc file associated with an edited file's project for the presence of four properties whose defaults are shown below. These rules, which are part of the ESLint-plugin-React EsLint plugin, are then used to determine the alignment and tab/spaces spacing of JSX elements. For more information on the options for these rules see Closing bracket, Indent and Indent Props.

Please note that no attempt is currently made to read eslint settings in any other file. e.g. package.json, eslint.js, extends..., etc.

{
  "rules": {
    "indent": 1,
    "react/jsx-closing-bracket-location": 1,
    "react/jsx-indent-props": 1,
    "react/jsx-indent": 1
  }
}

When moving around a JSX block language-babel reformats the preceding JSX lines automatically. Lines following the cursor are not indented. This is to protect the source code following incomplete JSX from being processed. The user should correctly position the first JSX element as auto-indenting will not do this.

You may also turn off automatic indenting for all files by setting the package option Auto Indent JSX

language-babel fully supports the Babel JavaScript transpiler versions 5 and 6.

Options in the language-babel package settings and/or in .languagebabel project based JSON files allow for Babel validations to be carried out on a file saves using .babelrc options. A file tree context menu - Language-Babel - is also provided that allows whole directories to be transpiled obeying any .babelrc and .languagebabel settings. Even if using a workflow such as gulp, webpack, etc, this can be very useful. Additional options allow the output from Babel (transpiled code and maps ) to be output to other directories.

It is also possible to preview any source file as Babel would output it.

Babel v5 and Babel v6 code can be previewed as shown bellow. Source mapping keeps the ES201x file's cursor in step with the transpiled code's cursor. This feature requires the Atom package source-preview in which language-babelbecomes a provider of transpiled output which source-preview consumes.

Please note that the following two packages should be disabled or uninstalled to stop multiple packages contending for the same transpile - source-preview-babel and source-preview-react.

source-preview provides a keyboard toggle to view the current file. As with transpiling described below, a project must have the relevant .babelrc, package.json and node_modules

This package works by using the concept of a project folder which we assume contains a project or even nested projects any of which may contain a Babel project. In a Babel project we expect to see one or more .babelrc files, node_modules folders at the root's of the project containing an optional babel-core (either v5 or v6) and other babel plugins/presets as determined by the project's package.json file. In addition we may expect to see one or more .languagebabel files in the project. Projects are either implicit (an Atom project folder) or explicit (denoted by a .languagebabel property of "projectRoot": true). If no babel-core is found in the project then a version will be provided by the package but this will be a Babel Version 6 instance. Plugins and presets will not be provided by the package.

A trivial example project that shows examples of using .languagebabel and .babelrc files may be found here.

Multiple projects may be open at any time inside Atom and language-babel must allow the use of differing babel-core versions and associated plugins when transpiling. It does this by using background tasks - one per Babel project. When a language-babel grammar enabled file is saved the package settings and optionally any .languagebabel configuration files are read to determine if the file should be transpiled and what to do with the output. These settings and .languagebabel options are described below.

It is very easy to ensure that language-babel does not transpile files that are not needed. Just turn off the global package setting Transpile On Save and turn on Allow Local Override. Apart form grammar highlighting only projects having a .languagebabel in the file path will then be affected by this package. Further granularity is easy too.

If .babelrc and/or package.json files contain Babel properties that are environment specific these environments should be created before Atom is started. In particular, Babel assumes a development environment by default, whereas Atom assumes a production environment by default.

e.g.

Windows

set NODE_ENV="development"
atom

OSX/Unix

NODE_ENV="development"
atom

For most projects it is better to configure language-babel via project based .languagebabel file properties which will override the package settings below. See ".langeuagebabel Configuration" for more information on this behaviour.

• Allow Local Override

  If set this allows .languagebabel file properties to be override the global package settings.

• Transpile On Save

  On any file save of a language-babel grammar enabled file the Babel transpiler is called. No actual transpiled file is saved but any Babel errors and/or successful indicators are notified by an ATOM pop-up. Not all files are candidates for transpilation as other settings can affect this. For example see Disable When No Babelrc File In Path and Babel Source Path below.

  {"transpileOnSave": true} or
  {"transpileOnSave": false}

• Create Transpiled Code

  If enabled together with Transpile On Save this will output JavaScript code to a .js file with the same prefix as the original. By using the Babel Transpile Path options it is possible to transpile to a different target directory. Not all files are candidates for transpilation as other settings can affect this.

  {"createTranspiledCode": true} or
  {"createTranspiledCode": false}

• Disable When No Babelrc File In Path

  Disables transpiler if no .babelrc files are found in the source file path.

  {"disableWhenNoBabelrcFileInPath": true} or
  {"disableWhenNoBabelrcFileInPath": false}

• Suppress Transpile On Save Messages

  Suppress all successful save messages. Errors are still notified.

  {"suppressTranspileOnSaveMessages": true} or
  {"suppressTranspileOnSaveMessages": false}

• Suppress Source Path Messages

  This is set by default so that when a file is saved that is outside the Babel Source Path directory no message is generated. This is particularly useful when you have mixed ES2015 and ES3-5 environment. ES2015 files can be placed inside a Babel Source Path where they will be transpiled and other files will not pop up annoying messages when being saved.

  {"suppressSourcePathMessages": true} or
  {"suppressSourcePathMessages": false}

• Create Map

  If transpiled output is being saved a separate source map can be also be saved. The source file name will be used with a new suffix of .js.map and sent to a directory specified in Babel Maps Path. To avoid any possible XSSI issues the map file is prefixed with )]}

  If .babelrc files use sourceMaps: inline or sourceMaps both options then turn this option off as the map data is stored as part of the source file.

  {"createMap": true} or
  {"createMap": false}

• Babel Maps Add Url

  If a source map is created using the Create Map option this allows a Url reference //# sourceURL=originalBabelSourcefile to be appended to the generated transpiled JavaScript file.

  {"babelMapsAddUrl": true} or
  {"babelMapsAddUrl": false}

• Project Root ( only present in .languagebabel files)

  A .languagebabel property that defines this directory is a project root. A project root would contain a node_modules folder with an optional babel-core as well as any plugins required.

  {"projectRoot": true} or
  {"projectRoot": false}

• Babel Source Path, Babel Transpile Path and Babel Maps Path

  These a directories based on the project root. A project root is either implicit ( baed on an Atom folders root directory) or explicit ( based upon the root defined in the nearest .languagebabel file with a property "projectRoot": true )

  Only files found under the project/babelsourcepath will be candidates for transpilation. If multiple project root folders exist then babelsourcepath may exist in any or all folders.

  The Transpile and Maps paths allow different target directories to be specified. If multiple project root folders exist then they may exist in any or all folders.

  e.g. Two project root folders exist /proj1 and /proj2. If Source Path is set to babelSourcethe Transpile Path is set to babelTranspile and the Maps Path is set to babelMaps then:-

  /proj1/babelSource/foo.es6 ->/proj1/babelTranspile/foo.js,/proj1/babelMaps/foo.js.map

  {
    "projectRoot":  true,    
    "babelSourcePath": "babelSource",
    "babelTranspilePath": "babelTranspile",
    "babelMapsPath": "babelMaps"
  }

  /proj2/babelSource/dirBar/foo.es6 -> /proj2/lib/foo.js,/proj2/lib/foo.js.map

  {
    "projectRoot":  true,
    "babelSourcePath": "babelSource/dirBar",
    "babelTranspilePath": "lib",
    "babelMapsPath": "lib"
  }

• Create Target Directories

  When enabled any target directories that do not exist will be created prior to a transpilation.

  {"createTargetDirectories": true} or
  {"createTargetDirectories": false}

• Auto Indent JSX

  Enables automatic indenting of JSX.

.languagebabel JSON configuration files can exist in any directory of the path that contains a source file to be compiled. The properties in this file override the global package settings above. If .languagebabel files are present, they read and merged starting in the source files directory up to the project root directory. Properties defined closest the source file take precedence.

To use this option please enable the Allow Local Override package setting.

A .languagebabel file may contain one or more of the following properties.

{
  "babelMapsPath":                    "relPath",
  "babelMapsAddUrl":                  true|false,
  "babelSourcePath":                  "relPath",
  "babelTranspilePath":               "relPath",
  "createMap":                        true|false,
  "createTargetDirectories":          true|false,
  "createTranspiledCode":             true|false,
  "disableWhenNoBabelrcFileInPath":   true|false,
  "projectRoot":                      true|false,  
  "suppressSourcePathMessages":       true|false,
  "suppressTranspileOnSaveMessages":  true|false,
  "transpileOnSave":                  true|false
}