mini-include.js

var fs = require('fs');

function resolve (path, visited) {
  visited.push(path);
  var fileString = fs.readStringFromFile(path);
  if (fileString.contains("<include")) {
    var includeIdxs = fileString.indexesOf("<include");
    includeIdxs.forEach(function (includeIdx, i) {
      var secondPath = fileString.readTilNext(includeIdx, '>');
      if (visited.indexOf(secondPath) >= -1) {
        throw new Error('Invalid cyclical dependency');
      }
      var secondResolve = resolve(secondPath, visited); 
      visited.pop();
      var includeLen = secondPath.length + 10;
      fileString.replace(includeIdx, includeLen, secondResolve);
      if (i < includeIdxs.length - 1) {
        includeIdxs[i + 1] += secondResolve.length - includeLen;
      }
    });
  }
  return fileString;
}

var visited = [];
resolve('a.script', visited);

Pardon the var fs at the top. Just trying to get my in-vim jslint to shut up.