add js colorway example

Author: michaelbabyn

_posts/plotly_js/style/colorway/2018-10-03-colorway.html

@@ -0,0 +1,33 @@
+---
+name: Set Default Trace Colors with colorway
+plot_url: https://codepen.io/plotly/embed/jeqNBq/?height=500&theme-id=15263&default-tab=result
+language: plotly_js
+suite: colorway
+order: 1
+sitemap: false
+arrangement: horizontal
+---
+
+var linspace = require('linspace');
+const parabolaGen = (a, b) =>
+  x => x*x*a + b;
+
+var as = linspace(1, 3, 7);
+var bs = linspace(2, 14, 7);
+var x = linspace(-1, 3, 50);
+var data = [];
+
+for (i=0; i< as.length; i++ ){
+  data.push({
+    type: "scatter",
+    mode: "lines",
+    x: x,
+    y: x.map(parabolaGen(as[i],bs[i]))
+  })
+}
+
+var layout = {
+  colorway : ['#f3cec9', '#e7a4b6', '#cd7eaf', '#a262a9', '#6f4d96', '#3d3b72', '#182844']
+};
+
+Plotly.newPlot('myDiv', data, layout);

_posts/plotly_js/style/colorway/2018-10-03-colorway_plotlyjs_index.html

@@ -0,0 +1,16 @@
+---
+title: Colorway in JavaScript.
+name: Colorway
+permalink: javascript/colorway/
+description: How to use colorway to set default trace colors in Javascript with Plotly.
+layout: base
+thumbnail: thumbnail/colorway.jpg
+language: plotly_js
+page_type: example_index
+has_thumbnail: true
+display_as: style_opt
+order: 3
+---
+
+{% assign examples = site.posts | where:"language","plotly_js" | where:"suite","colorway" | sort: "order" %}
+{% include auto_examples.html examples=examples %}

_posts/r/style/2018-10-03-colorway.Rmd

@@ -7,6 +7,7 @@ layout: base
 language: r
 page_type: example_index
 has_thumbnail: true
+thumbnail: thumbnail/colorway.jpg
 display_as: style_opt
 order: 5
 output:
@@ -37,7 +38,7 @@ library(plotly)
 packageVersion('plotly')
 ```
 
-### Set Default Trace Colors with colorway
+### Set Default Trace Colors with `colorway`
 
 ```{r, results = 'hide'}
 library(plotly)

_posts/r/style/2018-10-03-colorway.md

@@ -7,6 +7,7 @@ layout: base
 language: r
 page_type: example_index
 has_thumbnail: true
+thumbnail: thumbnail/colorway.jpg
 display_as: style_opt
 order: 5
 output:
@@ -38,7 +39,7 @@ packageVersion('plotly')
 ## [1] '4.8.0'
 ```
 
-### Set Default Trace Colors with colorway
+### Set Default Trace Colors with `colorway`
 
 
 ```r