JSPP

JSPP is a pre-compiler with Javascript syntax, similar in function to C's CPP. You could use JSPP for many languages but it's naturally suitable for Javascript.

When used with Javascript, JSPP adds the following functionality:

• File inclusion
• Conditional code inclusion
• Macro expansion

If you're writing serious Javascript and don't intend to use m4, then I suggest you take a look at these examples.

• Example 1: Including a file (similar to #include "file")

  $ jspp File1.js > output.js
  

  File1.js

    #include File2.js
    helloworld();
  

  File2.js

    function helloworld() { alert("Hello world!") }
  

  output.js

    function helloworld() { alert("Hello world!") }
    helloworld();
  

• Example 2: Conditional code (similar to #ifdef/#endif)

  $ jspp File1.js > output.js
  

  File1.js

    #var debug=1;
    #if (debug) {
    function stderr(a) { alert(a) }
    #} else {
    function stderr(a) { }
    #}
  
    stderr('My program has started');
  

  output.js

    function stderr(a) { alert(a) }
  
    stderr('My program has started');
  

• Example 3: Macro expansion

  $ jspp File1.js > output.js
  

  File1.js

    #function strlen(a) { emit(a+'.length()') }
    var mystr='hello';
    #emit("print('mystr has length: '+");
    #strlen('mystr');
    );
    
    #emit('alert("Hi world");\n');
    alert("The end");
  

  output.js

    var mystr='hello';
    print('mystr has length: '+mystr.length());
    
    alert("Hi world");
    alert("The end");
  

• Example 4: Libraries

  $ jspp File1.js > output.js
  

  File1.js

    #var uses={strlen:1,atoi:1};
    #include File2.js
    alert(atoi('4')+' = '+strlen('abcd'));
  

  File2.js

    #if (uses['strlen']) {
    function strlen(a) { return (''+a).length }
    #}
    #if (uses['atoi']) {
    function atoi(a) { return parseInt(a) }
    #}
    #if (uses['atof']) {
    function atof(a) { return parseFloat(a) }
    #}
  

  output.js

    function strlen(a) { return (''+a).length }
    function atoi(a) { return parseInt(a) }
    alert(atoi('4')+' = '+strlen('abcd'));
  

• Example 5: As a CGI

  This is not ideal for production servers but it works well enough for development.

  $ chmod +x program.sh
  

  program.sh

    #!/bin/sh
    echo "Content-type: text/javascript"
    echo
    
    jspp program.js
  

• Example 6: Including a directory of files

  $ make
  

  project.js

    #include project//*.js
  

  project/1.js

    function one() {}
  

  project/2.js

    function two() {}
  

  Makefile

    AJS=$(shell ls project/*.js)
    JS=project.js ${AJS}
    
    xproject.js: ${JS}
    	jspp project.js > xproject.js
  

  xproject.js

    function one() {}
    function two() {}
  

Notes

	JSPP is released under the GPL
	It is written in C
	It should compile on any unixy system, e.g. Linux
	It has not yet been ported to Windows
	It wants a Javascript shell installed, such as Mozilla's Spidermonkey ($ apt-get install spidermonkey-bin)
	Processing foreign code can't exec arbitary code (when used with Spidermonkey)
	You can run "$ jspp -p project.js | less" to see the Javascript it passes to the shell
	You can run "$ jspp -p project.js | js - | less" to see what the shell passes back

To Do: Write full documentation

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Download source code (version 0.02, 17k)