For writing to a debug document in Google Apps Script

javascript_debugging.js

DEBUG_DOC_ID = "Replace this with the ID of document to write debug output to";

function print_r (array) {
  var analyze = function(array) {
    return format(array, 0);
  }
  var format = function(obj, depth) {
    var str = "";
    var padder = "";
    var PAD = "    ";
    for (var i = 0; i < depth; i++) {
      padder += PAD;
    }
    if (typeof obj === 'object') {
      str += obj.constructor.name;
      if (obj.constructor.name === "Array" || obj.constructor.name === "Object") {
        var q = (obj.constructor.name === "Array") ? "" : "'";
        str += "\n" + padder + "(\n";
        for (var i in obj) {
          str += padder + PAD + "[" + q + i + q + "] => " + format(obj[i], depth + 1) + "\n";
        }
        str += padder + ")\n";
      }
    } else if (typeof obj === 'string') {
      str += "'" + obj.toString() + "'";
    } else {
      str += obj.toString();
    }
    return str;
  }
  debugln(analyze(array));
}

function debugln(msg) {
  var doc = DocumentApp.openById(DEBUG_DOC_ID);
  doc.getBody().setText(doc.getBody().getText() + msg + "\n");
}

function cleardebug(msg) {
  var doc = DocumentApp.openById(DEBUG_DOC_ID);
  doc.getBody().setText("");
}