From e82645d52bcef1d74ef0edefff2cdcc1c51efcf3 Mon Sep 17 00:00:00 2001
From: Stefan Eckert <MrTelanie@gmail.com>
Date: Fri, 7 Sep 2018 00:05:40 +0200
Subject: [PATCH] feat(formatter): optimize formatter for rounded values

---
 src/formatter.js  | 25 +++++++++++++++----------
 test/formatter.js |  3 ++-
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/formatter.js b/src/formatter.js
index ec7e5014..46627e67 100644
--- a/src/formatter.js
+++ b/src/formatter.js
@@ -1,11 +1,9 @@
 // https://code.open-xchange.com/#contentPanel;a7550a02-aa41-45d9-9cad-7e1c920815f3;null;ui/apps/io.ox/office/tk/utils.js;content
 
-const MULTIPLIER = 7;
-
 function normalizeNumber(number) {
   // special handling for zero
   if (number === 0) {
-    return { mant: 0, exp: 1 };
+    return { mant: 0, exp: 2 };
   }
 
   let exp = Math.floor(Math.log(Math.abs(number)) / Math.LN10);
@@ -23,21 +21,28 @@ function normalizeNumber(number) {
     exp += 1;
   }
 
-  for (let i = 0; i <= MULTIPLIER; i += 1) {
-    mant /= 10;
-    exp += 1;
-  }
-
   return { mant, exp };
 }
 
 export default function formatNumber(nr, digits) {
   const n = normalizeNumber(nr);
+  n.mant /= 10;
+  n.exp += 1;
+
   const p = digits || 4;
-  const rounder = 10 ** (p + MULTIPLIER);
+  const rounder = 10 ** Math.max(n.exp, p);
 
-  const mant = Math.round(n.mant * rounder) / rounder;
+  let mant = Math.round(n.mant * rounder) / rounder;
+  if (mant === 1) {
+    mant /= 10;
+    n.exp += 1;
+  }
 
+  if (n.exp <= 1) {
+    mant = mant.toString().replace('0.', '');
+
+    return `0.${'0'.repeat(Math.max(0, -n.exp))}${mant}`;
+  }
   const e = 10 ** n.exp;
   return mant * e;
 }
diff --git a/test/formatter.js b/test/formatter.js
index d9074b31..c62d6281 100644
--- a/test/formatter.js
+++ b/test/formatter.js
@@ -7,8 +7,9 @@ describe('formatNumber test.', () => {
     assert.equal(formatNumber(0.00009998), '0.00009998');
     assert.equal(formatNumber(0.00000000000000000001), '0.00000000000000000001');
     assert.equal(formatNumber(0.0000000000000000000000000001), '0.0000000000000000000000000001');
+    assert.equal(formatNumber(0.00009999999999), '0.0001');
     assert.equal(formatNumber(0.00009999), '0.00009999');
     assert.equal(formatNumber(257.5657), '257.6');
-    assert.equal(formatNumber(2575657546445.985), '2576000000000');
+    assert.equal(formatNumber(2575657546445.985), '2575657546446');
   });
 });