JS verifies floating-point regular expressions

/*

*/
 /**
  * Floating point decision
  * @param type
  *   null    arbitrary floating-point number   *   ' 0+ '   nonnegative floating-point number
  *   ' + '    positive floating-point number
  *   '-0 '   Non-positive floating-point number
  *   '-'    negative floating-point number
  */

 function isfloat (type) {
  var RT = new Array ();
  if (type== "0+") {
   rt[0] = "^\d+ (. \d+)? $";
   rt[1] = "non-negative floating-point number should be entered!";
  }else if (type== "+") {
   rt[0] = "^" (\d+\.\d*[1-9]\d*) | ( \d*[1-9]\d*\.\d+) | (\d*[1-9]\d*)) $";
   rt[1] = "The positive floating-point number should be entered!";
  }else if (type== "-0") {
   rt[0] = "^ (-\d+ (. \d+)?) | (0+ (\.0+)) $";
   rt[1] = "non-positive floating-point number should be entered!";
  }else if (type== "-") {
   rt[0] = "^ (-(\d+\.\d*[1-9]\d*) | ( \d*[1-9]\d*\.\d+) | (\d*[1-9]\d*))) $";
   rt[1] = "Negative floating-point number should be entered!";
  }else{
   rt[0] = "^ (-?\d+) (\.\d+)? $";
   rt[1] = "Floating-point value should be entered!";
  }
  return RT;
 }