isNumeric and other suggestions by Alex

(cherry picked from commit 66f1641)

Author: monfera

src/traces/table/data_preparation_helper.js

@@ -10,6 +10,7 @@
 
 var c = require('./constants');
 var extendFlat = require('../../lib/extend').extendFlat;
+var isNumeric = require('fast-isnumeric');
 
 // pure functions, don't alter but passes on `gd` and parts of `trace` without deep copying
 module.exports = function calc(gd, trace) {
@@ -32,9 +33,10 @@ module.exports = function calc(gd, trace) {
     var uniqueKeys = {};
     var columnOrder = trace._fullInput.columnorder;
     var columnWidths = headerValues.map(function(d, i) {
-        return Array.isArray(trace.columnwidth) ?
-            Number(trace.columnwidth[Math.min(i, trace.columnwidth.length - 1)]) :
-            trace.columnwidth !== null && isFinite(Number(trace.columnwidth)) ? Number(trace.columnwidth) : 1;
+        var value = Array.isArray(trace.columnwidth) ?
+            trace.columnwidth[Math.min(i, trace.columnwidth.length - 1)] :
+            trace.columnwidth;
+        return isNumeric(value) ? Number(value) : 1;
     });
     var totalColumnWidths = columnWidths.reduce(function(p, n) {return p + n;}, 0);