convert1.js

/*
 convert.js by chuck
 
 2015.9.5 start to work 
 2015.9.7 revision
 
 convert.js enables you to convert date to other data type

 TODO : 
 'tolerantCheck' is not good enough as a name of the function.
 {y !== undefined} in 'illegalDataType' is actually  not necessary
 '' (empty string) and 'undefined' isn't valid corrently.
 Maybe same data type convert should be error 
 
*/

var log = function(x) {console.log(x);}

var 
  usage = "Usage : \n 1st arg : data to convert. \n 2nd arg : data type to convert(not necessary).\n ex) cnv(false,'number');",
  soleArg = "You can also use 2nd arg as data type.",
  typeErr = 'type error! Only number, boolean or string are valid.';

var tolerantCheck = function(x) {
  return x !== undefined && (x === 0 || isNaN(x) || x === null);
};

var illegalDataType = function(y) {
  var illegal = y !== undefined && y !== 'number' && y !== 'boolean' && y !== 'string'; 
  illegal && log(typeErr);
  return illegal;
};

var hasArgs = function(x, y) {
  var 
    hasX = !!x || tolerantCheck(x),
    hasY = !!y,
    el = (!hasX && !hasY) ? usage : (hasX && !hasY) ? soleArg : null;
  el && log(el);
  return hasX ;
};

var convert = function(x, y) {
  var rtn;
  switch(y){
    case 'number':
      rtn = parseInt(x);
      break;
    case 'boolean':
      rtn = !!x;
      break;
    case 'string':
      rtn = x + '';
      break;
    case undefined:
      rtn = '{ number : ' + parseInt(x) + ' , boolean : ' + !!x + ' , string : ' + x + ' }';
      break;
    default:
  }
  return rtn;
};

var cnv = function(x, y) {
  if( !hasArgs(x, y) || illegalDataType(y) ) {
    return false;
  }
  var dataType = ( y ) ? '(' + y + ')' : null ;
  log(dataType + x + ' -> ' + convert(x, y) );
};