pocketrocket / floatify

var floatify = function floatify(str) {

  var toFloatFormat = function toFloatFormat(str, ts, ds) {

    var string = str;

    var decimalSeparator = ds || '';

    string = string.split(ts || '').join('');

    if (decimalSeparator !== '') {

      string = string.split(decimalSeparator).join('.');

    }

    return parseFloat(string);

  };

  var parseParts = function parseParts(str, ele, count) {

    var string = str;

    var element = ele;

    var parts = string.split(element);

    for (var i = 1; i < parts.length; i++) {

      var left = parts[i - 1];

      var leftVal = parseInt(left, 10);

      if (parts[i].length === 0) {

        return Number.NaN;

      }

      if (parts[i].length === 3) {

        if (left.length > 3 && parts.length - 1 !== i) {

          return Number.NaN;

        }

        if (

          (leftVal === 0 || isNaN(leftVal) || left.length > 3) && parts.length - 1 === i

        ) {

          return toFloatFormat(string, '', element);

        }

        continue;

      }

      if (i < parts.length - 1) {

        // violation in midPart -> NaN

        return Number.NaN;

      }

      // violation in end -> Could be decimalSeparator

      if (count === 1) {

        return toFloatFormat(string, '', element);

      }

      return Number.NaN;

    }

    return toFloatFormat(string, element, '');

  };

  var parse = function parse(str) {

    var string = str;

    var spacePos;

    var spaceSplit;

    var spaceCount;

    var dotPos;

    var commaPos;

    var lDotPos;

    var lCommaPos;

    var dotCount;

    var commaCount;

    string = string.trim();

    // 1st dot position

    dotPos = string.indexOf('.');

    // 1st comma position

    commaPos = string.indexOf(',');

    // 1st space position

    spacePos = string.indexOf(' ');

    if (dotPos + commaPos + spacePos === -3) {

      // life is good, no separators

      return toFloatFormat(string);

    }

    spaceSplit = string.split(' ');

    spaceCount = spaceSplit.length - 1;

    dotCount = string.split('.').length - 1;

    commaCount = string.split(',').length - 1;

    // only combination of 2 separators allowed

    if (dotCount > 0 && commaCount > 0 && spaceCount > 0) {

      return Number.NaN;

    }

    // if there is any separator (space, comma, dot) found more than once,

    // all other must not be found more than once

    if (dotCount > 1 && (commaCount > 1 || spaceCount > 1)) {

      return Number.NaN;

    }

    if (commaCount > 1 && spaceCount > 1) {

      return Number.NaN;

    }

    if (spaceCount > 0) {

      if (!string.match(/^(\d{1,3})?(\s\d{3})*([,\.]\d+)?$/)) {

        return Number.NaN;

      }

      string = spaceSplit.join('');

    }

    if (dotPos !== -1 && commaPos !== -1) {

      // format is using dot and comma

      // last dot position

      lDotPos = string.lastIndexOf('.');

      // last comma position

      lCommaPos = string.lastIndexOf(',');

      // order of 1st dot -> comma must be same as last dot -> comma

      // 123.123.123,123 -> ok 123.123,123.123 -> not ok

      if (Math.sign(dotPos - commaPos) !== Math.sign(lDotPos - lCommaPos)) {

        return Number.NaN;

      }

      // check positions to guess the thousands separator

      if (dotPos > commaPos) {

        if (dotCount > 1) {

          return Number.NaN;

        }

        // best guess: . is thousands separator and , is decimal point

        return toFloatFormat(string, ',', '.');

      }

      if (commaCount > 1) {

        return Number.NaN;

      }

      // best guess: , is thousands separator and . is decimal point

      return toFloatFormat(string, '.', ',');

    }

    if (dotPos !== -1) {

      // only dot(s) in format

      return parseParts(string, '.', dotCount);

    }

    if (commaPos !== -1) {

      // only comma(s) in format

      return parseParts(string, ',', commaCount);

    }

    return toFloatFormat(string);

  };

  return parse(str);

};