simplify ensureNumber

Author: archmoj

src/constants/numerical.js

@@ -15,7 +15,7 @@ module.exports = {
      * to avoid glitches: Make sure that even when you multiply it by the
      * number of pixels on a giant screen it still works
      */
-    FP_SAFE: Number.MAX_VALUE / 10000,
+    FP_SAFE: Number.MAX_VALUE * 1e-4,
 
     /*
      * conversion of date units to milliseconds

src/lib/index.js

@@ -5,7 +5,8 @@ var utcFormat = require('d3-time-format').utcFormat;
 var isNumeric = require('fast-isnumeric');
 
 var numConstants = require('../constants/numerical');
-var FP_SAFE = numConstants.FP_SAFE;
+var MAX_SAFE = numConstants.FP_SAFE;
+var MIN_SAFE = -MAX_SAFE;
 var BADNUM = numConstants.BADNUM;
 
 var lib = module.exports = {};
@@ -166,8 +167,7 @@ lib.cleanNumber = require('./clean_number');
 lib.ensureNumber = function ensureNumber(v) {
     if(!isNumeric(v)) return BADNUM;
     v = Number(v);
-    if(v < -FP_SAFE || v > FP_SAFE) return BADNUM;
-    return isNumeric(v) ? Number(v) : BADNUM;
+    return (v > MAX_SAFE || v < MIN_SAFE) ? BADNUM : v;
 };
 
 /**