Flatten a json

jsonflatenner.js

function json_structure_test(){

  var json = {
    'toto':{
      'titi':{
        'tata': 'Hello World',
        'lala': 'lulu'
      }
    },
    'cucu':'coco'};
  
  var json2 = {
    'toto': 'tata',
    'titi': 'tutu',
    'lala': {
             'lili':'lele',
             "lol":"luz",
      "roro":{'gigi':'lppl'}
            }
  }
  
  var flattened = flattenJson_(json2, {}, undefined, 0);
  Logger.log(flattened);
  
  if(flattened['toto'] != 'tata' || flattened['titi'] != 'tutu'){
    throw new ExectionException("Problem");
  }
  
  if(flattened['lala.lili'] != 'lele'){
    throw new ExectionException("Problem");
  }
  
  if(flattened['lala.lol'] != 'luz'){
    throw new ExectionException("Problem");
  }
  
  if(flattened['lala.roro.gigi'] != 'lppl'){
    throw new ExectionException("Problem");
  }
  
}

/**
 * Flatten the json according the following model:
 *
 * {
    'toto': 'tata',
    'titi': 'tutu',
    'lala': {
             'lili':'lele',
             "lol":"luz",
      "roro":{'gigi':'lppl'}
            }
  }
 *
 * gives
 *
 *  {toto=tata, lala.lol=luz, lala.roro.gigi=lppl, titi=tutu, lala.lili=lele}
 *
 *
 * @param inputJson  Json to flatten
 * @param outputJson Object bucket where to accumulate new entry/value pairs
 * @param localTable inner var
 * @param depth      recursivity depth
 * @returns The flatenned json
 * @private
 */
function flattenJson_(inputJson, outputJson, localTable, depth) {
    // we are in a json final node
    if (inputJson !== null && typeof inputJson !== 'object') {
        var finalTable = localTable.slice(); // we need to shallow copy the array to not modify other references
        var level = finalTable.join(SEPARATOR); // constant separator
        outputJson[level] = inputJson;
    }

    for (var key in inputJson) {
        if (depth == 0) { // first key
            var line = [key];
            flattenJson_(inputJson[key], outputJson, line, depth + 1);
        } else { // we agregate the current path element in the localtable that will contain all the path in the end.
            var table = localTable.slice();
            table.push(key);
            flattenJson_(inputJson[key], outputJson, table, depth + 1);
        }
    }
    return outputJson;
}