Highly performant key=value string parser

command-line-query-parser.js

// CommonJS
exports.getFlagValues = function (queryCommand = "") {
  let FlagValuesObject = {};
  const stringParts = queryCommand
    .split(" ")
    .map((part) => part.replace(/["']/g, ""));

  let valueCompleted = true;
  let accummulator_key = "";
  let accummulator_value = [];

  const splitParts = stringParts.map((part) => part.split("=")).filter(part => part[0] !== "");

  for (let i = 0; i < splitParts.length; i++) {
    if (i === 0) {
      //  dont do anything ignore the command part
    } else {
      if (splitParts.length - 1 === i) {
        // we have reached the end  
        if (valueCompleted === false) {
          accummulator_value.push(splitParts[i][0])
          FlagValuesObject[accummulator_key] = accummulator_value.join(" ")
        }
      } else {
        // we have not reached the last item yet
        // we get to the current item less than 2
        if (splitParts[i].length < 2) {
          valueCompleted = false
          // check the value before this
          if (splitParts[i - 1].length > 1) {
            accummulator_key = splitParts[i - 1][0]
            accummulator_value.push(splitParts[i - 1][1])
            accummulator_value.push(splitParts[i][0])
          } else {
            accummulator_value.push(splitParts[i][0])
          }
        }
      }

      if (splitParts[i].length > 1) {
        if (valueCompleted === true) {
          FlagValuesObject[splitParts[i][0]] = splitParts[i][1]
        } else {
          if (splitParts.length - 1 === i) {
            // we are done accumulating
            valueCompleted = true
            FlagValuesObject[accummulator_key] = accummulator_value.filter((_,idx) => accummulator_value.length - 1 !== idx).join(" ")
            accummulator_value = accummulator_value.filter(() => false)
            accummulator_key = ""
            FlagValuesObject[splitParts[i][0]] = splitParts[i][1]
          } else {
            // we are done accumulating
            valueCompleted = true
            FlagValuesObject[accummulator_key] = accummulator_value.join(" ")

            // reset
            accummulator_value = accummulator_value.filter(() => false)
            accummulator_key = ""
            
            FlagValuesObject[splitParts[i][0]] = splitParts[i][1]
          }
        }
      } else {
        if (splitParts.length > i && valueCompleted === true) {
          // get the last but one item
          let keyBefore = splitParts[i - 1][0]
          let valueBefore = splitParts[i - 1][1]

          // add the last but one item
          FlagValuesObject[keyBefore] = valueBefore.split(" ") + " " + splitParts[i][0]
        }
      }
    }
  }

  return FlagValuesObject;
};