Package Exports

preprocess
preprocess/lib/regexrules

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (preprocess) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

preprocess

Preprocess HTML, JavaScript, and other files with directives based off custom or ENV configuration

What does it look like?

<head>
  <title>Your App

  <!-- @if NODE_ENV='production' -->
  <script src="some/production/lib/like/analytics.js"></script>
  <!-- @endif -->
  
</head>
<body>
  <!-- @ifdef DEBUG -->
  <h1>Debugging mode - <!-- @echo RELEASE_TAG --> </h1>
  <!-- @endif -->
  <p>
  <!-- @include welcome_message.txt -->
  </p>
</body>

var configValue = '/* @echo FOO */' || 'default value';

// @ifdef DEBUG 
someDebuggingCall()
// @endif

Directive syntax

Simple syntax

The most basic usage is for files that only have two states, non-processed and processed. In this case, your @exclude directives are removed after preprocessing

<body>
    <!-- @exclude -->
    <header>You're on dev!</header>
    <!-- @endexclude -->
</body>

After build

<body>
</body>

Advanced directives

@if VAR='value' / @endif This will include the enclosed block if your test passes
@ifdef VAR / @endif This will include the enclosed block if VAR is defined (typeof !== 'undefined')
@ifndef VAR / @endif This will include the enclosed block if VAR is not defined (typeof === 'undefined')
@include This will include the source from an external file
@exclude / @endexclude This will remove the enclosed block upon processing
@echo VAR This will include the environment variable VAR into your source

Extended html Syntax

This is useful for more fine grained control of your files over multiple environment configurations. You have access to simple tests of any variable within the context (or ENV, if not supplied)

<body>
    <!-- @if NODE_ENV!='production' -->
    <header>You're on dev!</header>
    <!-- @endif -->

    <!-- @if NODE_ENV='production' -->
    <script src="some/production/javascript.js"></script>
    <!-- @endif -->

    <script>
    var fingerprint = '<!-- @echo COMMIT_HASH -->' || 'DEFAULT';
    </script>
</body>

With a NODE_ENV set to production and 0xDEADBEEF in COMMIT_HASH this will be built to look like

<body>
    <script src="some/production/javascript.js"></script>

    <script>
    var fingerprint = '0xDEADBEEF' || 'DEFAULT';
    </script>
</body>

With NODE_ENV not set or set to dev and nothing in COMMIT_HASH, the built file will be

<body>
    <header>You're on dev!</header>

    <script>
    var fingerprint = '' || 'DEFAULT';
    </script>
</body>

JavaScript, C, Java Syntax

Extended syntax below, but will work without specifying a test

normalFunction();
//@exclude
superExpensiveDebugFunction()
//@endexclude

'/* @echo USERNAME */'

anotherFunction();

Built with a NODE_ENV of production :

normalFunction();

'jsoverson'

anotherFunction();

Configuration and Usage

Install via npm

$ npm install --save preprocess

Use the exposed preprocess method or the convenience file functions. The context, by default, is the current ENV config the process (process.env)

var pp = require('preprocess');

var text = 'Hi, I am <!-- @echo USERNAME -->';

pp.preprocess(text);
// -> Hi, I am jsoverson

pp.preprocess(text, {USERNAME : "Bob"});
// -> Hi, I am Bob

// Simple wrapper around fs.readFile and fs.writeFile
pp.preprocessFile(src, dest, context, callback);

// Simple wrapper around fs.readFileSync and fs.writeFileSync
pp.preprocessFileSync(src, dest, context);

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using jshint

Release History

1.1.0 Added deep inclusion, fixed sequential ifs
1.0.1 Fixed multiple inline echo statements
1.0.0 Pulled from grunt-preprocess to stand alone

License

Written by Jarrod Overson

Licensed under the Apache 2.0 license.