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()
// @endifDirective 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'/@endifThis will include the enclosed block if your test passes@ifdef VAR/@endifThis will include the enclosed block if VAR is defined (typeof !== 'undefined')@ifndef VAR/@endifThis will include the enclosed block if VAR is not defined (typeof === 'undefined')@includeThis will include the source from an external file. If the included source ends with a newline then the following line will be space indented to the level the @include was found.@exclude/@endexcludeThis will remove the enclosed block upon processing@echo VARThis 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>You can also have conditional blocks that are hidden by default by using the
fictional !> end tag instead of --> after your condition:
<!-- @if true !>
<p>Process was run!</p>
<!-- @endif -->JavaScript, CSS, 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();CSS example
body {
/* @if NODE_ENV=='development' */
background-color: red;
/* @endif */
}
// @include util.css(CSS preprocessing supports single line comment style directives)
Shell, PHP
#!/bin/bash
# @include util.sh
Configuration and Usage
Install via npm
$ npm install --save preprocessUse 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
- 2.0.0 Added ability to echo strings, added conditional comments, removed lodash, merged 17, 13, 15, 16
- 1.2.0 Added processing for hash-style comments (via @marsch). Added more file aliases.
- 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
Copyright OneHealth Solutions, Inc
Written by Jarrod Overson
Licensed under the Apache 2.0 license.
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent