chore!: drop Node 6 support (#1461)

Benjamin E. Coe · web-flow · commit 2ba8ce05e8fe · 2019-10-26T19:43:39.000-07:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,11 +1,10 @@
 language: node_js
 
 node_js:
-  - "6"
   - "8"
   - "10"
-  # - "11" TODO: add 11 in April when 12 goes live.
-  - "node"
+  - "12"
+  - "13"
 
 os:
   - linux
diff --git a/yargs.js b/yargs.js
@@ -1,5 +1,9 @@
 'use strict'
 
+// an async function fails early in Node.js versions prior to 8.
+async function requiresNode8OrGreater () {}
+requiresNode8OrGreater()
+
 const argsert = require('./lib/argsert')
 const fs = require('fs')
 const Command = require('./lib/command')
