Drop support for node 6

.travis.yml

@@ -1,8 +1,8 @@
 language: node_js
 node_js:
-  - "6"
   - "8"
   - "10"
+  - "12"
 sudo: required
 before_script:
   - npm run all

README.md

@@ -33,7 +33,7 @@ Come on in, the water's lovely. More help? Ping `bhousel` or `quincylvania` on:
 
 ## Prerequisites
 
-* [Node.js](https://nodejs.org/) version 6 or newer
+* [Node.js](https://nodejs.org/) version 8 or newer
 * [`git`](https://www.atlassian.com/git/tutorials/install-git/) for your platform
   * Note for Windows users:
     * Edit `$HOME\.gitconfig`:<br/>

build_src.js

@@ -6,7 +6,7 @@ const json = require('rollup-plugin-json');
 const nodeResolve = require('rollup-plugin-node-resolve');
 const rollup = require('rollup');
 const shell = require('shelljs');
-// const visualizer = require('rollup-plugin-visualizer');
+const visualizer = require('rollup-plugin-visualizer');
 
 
 module.exports = function buildSrc() {
@@ -42,12 +42,11 @@ module.exports = function buildSrc() {
                         browser: false
                     }),
                     commonjs(),
-                    json({ indent: '' })
-                    // uncomment when we require node 8+
-                    // visualizer({
-                    //     filename: 'docs/statistics.html',
-                    //     sourcemap: true
-                    // })
+                    json({ indent: '' }),
+                    visualizer({
+                        filename: 'docs/statistics.html',
+                        sourcemap: true
+                    })
                 ]
             })
             .then(function (bundle) {

package.json

@@ -107,7 +107,7 @@
     ]
   },
   "engines": {
-    "node": ">=6.0.0",
-    "npm": ">=3.0.0"
+    "node": ">=8.0.0",
+    "npm": ">=5.0.0"
   }
 }