footprint.js

// (maybe) a way to approximate the current "footprint" of
// your javascript (in a firebug-enabled firefox).
//
// example:
//    footprint({
//      context : 'jQuery',
//      initial : true,
//      print   : true,
//      trace   : true,
//      debug   : true,
//      filter  : function(o) { return true; }
//    });

function footprint(options) {
  var options = $.extend({
    context : 'location',       // the top-level entry point.         e.g., context: jQuery
    initial : false,            // flag: include items loaded before this file
    print   : false,            // flag: print names and totals.
    trace   : false,            // flag: print keys.
    debug   : false,            // flag: print function bodies.
    filter  : false             // used to limit first-level entry.   e.g., filter:  function(o) { return o.foo !== undefined; }
  }, options);

  var overall = 0;
  var context = options.context;

  var output = {
    print : function(message, tail) {
      if(options.print) {
        console.log(message);
        if(tail) {
          console.log(' ');
        }
      }
    },

    trace : function(message) {
      if(options.trace) {
        console.log(message);
      }
    },

    debug : function(message, indent) {
      if(options.debug) {
        console.debug(message.replace(/^/gm, indent + '  > ').replace(/^(.{1,150}).*/gm, '$1'));
      }
    },
  };

  function footprint_for(o, result) {
    for(var key in o) {
      if(o.hasOwnProperty(key)) {
        result.progress += 1;

        var current = o[key];

        if(typeof current === 'object') {
          if(current.constructor == Array) {
            output.trace(result.indent + 'A: ' + key + ' (length: ' + current.length + ')');

            result.indent += '  ';
            for(var i = 0, n = current.length; i < n; i ++) {
              output.trace(result.indent + 'item ' + i + ':');
              footprint_for(current[i], result);
            }
            result.indent  = result.indent.substring(0, result.indent.length - 2);
          }
          else {
            output.trace(result.indent + 'O: ' + key);

            result.indent += '  ';
            footprint_for(current, result);
            result.indent  = result.indent.substring(0, result.indent.length - 2);
          }
        }
        else if(typeof current === 'function') {
          output.trace(result.indent + 'F: ' + key);
          output.debug(current.toString(), result.indent);

          result.indent += '  ';
          footprint_for(current.prototype, result);
          result.indent  = result.indent.substring(0, result.indent.length - 2);
        }
      }
    }
  }

  for(var key in window[context]) {
    if(! options.initial) {
      if(window.__footprint_initials__[context] && window.__footprint_initials__[context][key]) {
        continue;
      }
    }

    var o = window[context][key];

    if(o) {
      if( ! options.filter || options.filter(o)) {
        output.print(key);

        var result = { progress: 0, indent: '  '};
        footprint_for(o, result);

        overall += result.progress;

        output.print(key + ' subtotal: ' + result.progress, true);
      }
    }
  }

  output.print('total: ' + overall);
  return overall;
}

__footprint_initials__ = {};

for(var global in window) {
  __footprint_initials__[global] = {};

  try {
    for(var top in window[global]) {
      __footprint_initials__[global][top] = true;
    }
  }
  catch(e) {}
}