Fixing logic of separator placement

lib/index.js

@@ -5,41 +5,46 @@
  * @returns {String} Comma formatted number
  */
 module.exports = function commaNumber (number, separator) {
-  separator = typeof separator === 'undefined' ? ',' : ('' + separator)
+  separator = typeof separator === 'undefined' ? ',' : ('' + separator);
+  negativeFlag = number < 0;
 
   // Convert to number if it's a non-numeric value
   if (typeof number !== 'number') {
-    number = Number(number)
+    number = Number(number);
   }
 
   // NaN => 0
   if (isNaN(number)) {
-    number = 0
+    number = 0;
   }
 
   // Return Infinity immediately
   if (!isFinite(number)) {
-    return '' + number
+    return '' + number;
   }
 
-  var stringNumber = ('' + Math.abs(number))
-    .split('')
-    .reverse()
+  //Converting number to string
+  var strNumber = ('' + number);
 
-  var result = []
-  for (var i = 0; i < stringNumber.length; i++) {
-    if (i && i % 3 === 0) {
-      result.push(separator)
-    }
-    result.push(stringNumber[i])
+  //Removing '-' character if negative number
+  if(negativeFlag) {
+    strNumber = strNumber.substr(1);
   }
 
-  // Handle negative numbers
-  if (number < 0) {
-    result.push('-')
+  //Checking if number has a decimal
+  var decimalFlag = strNumber.indexOf('.') != -1;
+
+  //Setting reference index and computing nunber of separators
+  var referenceIndex = decimalFlag ? strNumber.indexOf('.') : strNumber.length;
+  var numberOfSeperators =  decimalFlag ? (Math.floor(referenceIndex/3) == referenceIndex/3 ? referenceIndex/3 - 1 : Math.floor(referenceIndex/3)) : (Math.floor(referenceIndex/3) == referenceIndex/3 ? referenceIndex/3 - 1 : Math.floor(referenceIndex/3));
+  for(var i = 1; i <= numberOfSeperators; i++) {
+    strNumber = strNumber.substr(0,referenceIndex - 3*i) + separator + strNumber.substr(referenceIndex - 3*i);
+  }
+
+  //Checking and adding negative sign
+  if(negativeFlag) {
+    strNumber = '-' + strNumber;
   }
 
-  return result
-    .reverse()
-    .join('')
+  return strNumber;
 }