Fix BenjaminVanRyseghem#190 Allow abbreviation precision for < 4

Currently for some reason when using abbreviations like `'0,0a`  you can't specify the number of visible digits of precision for any value less than 4. So while `'4,0a'` will change `1234567` to `1,234k` the result of `'3,0a'` is `1m` instead of `1.23m` as expected.

This is primarily caused by a conditional that skips setting the precision in the formatting.

This commit changes how the algorithm determines if decimal places will be required and how many are required. We first compute the abbreviated unitized value and then use the length of that value to determine how many decimal places will be required.

numbro.js

@@ -77,6 +77,11 @@
         this._value = number;
     }
 
+    function numberLength(number) {
+        if (number === 0) { return 1; }
+        return Math.floor(Math.log(Math.abs(number)) / Math.LN10) + 1;
+    }
+
     function zeroes(count) {
         var i, ret = '';
 
@@ -472,7 +477,6 @@
             forcedNeg = false,
             neg = false,
             indexOpenP,
-            size,
             indexMinus,
             paren = '',
             minlen,
@@ -551,30 +555,16 @@
                 format = format.replace('a', '');
             }
 
-            totalLength = Math.floor(Math.log(abs) / Math.LN10) + 1;
-
+            totalLength = numberLength(value);
             minimumPrecision = totalLength % 3;
             minimumPrecision = minimumPrecision === 0 ? 3 : minimumPrecision;
 
             if (intPrecision && abs !== 0) {
-
-                length = Math.floor(Math.log(abs) / Math.LN10) + 1 - intPrecision;
-
                 pow = 3 * ~~((Math.min(intPrecision, totalLength) - minimumPrecision) / 3);
-
                 abs = abs / Math.pow(10, pow);
-
-                if (format.indexOf('.') === -1 && intPrecision > 3) {
-                    format += '[.]';
-
-                    size = length === 0 ? 0 : 3 * ~~(length / 3) - length;
-                    size = size < 0 ? size + 3 : size;
-
-                    format += zeroes(size);
-                }
             }
 
-            if (Math.floor(Math.log(Math.abs(value)) / Math.LN10) + 1 !== intPrecision) {
+            if (totalLength !== intPrecision) {
                 if (abs >= Math.pow(10, 12) && !abbrForce || abbrT) {
                     // trillion
                     abbr = abbr + cultures[currentCulture].abbreviations.trillion;
@@ -593,6 +583,12 @@
                     value = value / Math.pow(10, 3);
                 }
             }
+
+            length = numberLength(value);
+            if (intPrecision && length < intPrecision && format.indexOf('.') === -1) {
+                format += '[.]';
+                format += zeroes(intPrecision - length);
+            }
         }
 
         // see if we are formatting

tests/numbro/format.js

@@ -106,6 +106,11 @@ exports.format = {
                 [123456789, '9 a', '123456789 '],
                 [1234567891, '10 a', '1234567891 '],
 
+                [1234567, '2 a', '1.2 m'],
+                [1234567, '3 a', '1.23 m'],
+
+                [0, '2a', '0'],
+
                 [18823.85, '6 a', '18823.9 '],
                 [188235.85, '6 a', '188236 '],
                 [1882357.85, '6 a', '1882.36 k'],