feat: added blog post for yargs 5.0.0 release (#29)

Author: bcoe

_posts/2016-08-14-yargs-5.md

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+---
+layout: blog
+title: yargs 5.0.0 Released
+excerpt: yargs 5.0.0 released
+---
+
+{::options parse_block_html="true" /}
+<div class="page-content align-items">
+<div class="page-box-full left">
+# yargs 5.0.0 Released
+
+_yargs 5.0.0 is currently published to the `next` tag. To try it out simply
+ type the following:_
+
+<pre><code class="hljs language-bash">npm cache clear; npm i yargs@next --save</code></pre>
+
+This release is an exciting one: we've both introduced several slick new
+features (command suggestions, option coercion); and taken the opportunity presented by a major release to cleanup
+inconsistencies with yargs' underlying API.
+
+## New Features
+
+### Recommended Commands
+
+I love how git's command-line-interface provides helpful suggestions when
+you accidentally type the wrong command:
+
+<pre>
+  <code class="hljs language-bash">git: 'comit' is not a git command. See 'git --help'.
+
+Did you mean this?
+	commit</code></pre>
+
+With the new `recommendCommands()` method, you can add this same functionality
+to your yargs applications:
+
+<pre>
+  <code class="hljs language-javascript">require('yargs')
+  .command('hello', 'hello command')
+  .command('goodbye', 'goodbye command')
+  .recommendCommands()
+  .argv</code></pre>
+
+<pre>
+  <code class="hljs language-bash">$ ./cli.js helo
+
+Commands:
+  hello    hello command
+  goodbye  goodbye command
+
+Did you mean hello?</code></pre>
+
+### Option Coercion
+
+yargs allows you to provide a `type` parameter for your options, hinting how the value
+should be interpreted, e.g., `array`, `boolean`, `string`.
+
+This works great for simple values, but folks routinely ask for more complex
+parsing options; as an example, people have asked for the ability to parse
+JSON:
+
+<pre><code class="hljs language-bash">$ ./cli.js -j '{"message": "hello world!"}'</code></pre>
+
+yargs' new coercion feature allows you to apply an arbitrary
+parsing function to your options:
+
+<pre><code class="hljs language-javascript">var argv = require('./')
+  .option('j', {
+    alias: 'json',
+    coerce: function (arg) {
+      return JSON.parse(arg)
+    }
+  })
+  .argv
+
+console.log(argv.json.message)</code></pre>
+
+<pre><code class="hljs language-bash">$ ./cli.js '{"message": "hello world!"}'
+
+hello world!</code></pre>
+
+I love the concept of coercion, it gives our users much more flexibility
+when parsing their arguments; without adding any significant complexity to
+yargs itself.
+
+## Breaking Changes
+
+yargs 5.0.0 introduces several breaking changes, read carefully!
+
+### Fixes to Command API
+
+yargs' [command API](https://github.com/yargs/yargs#commandcmd-desc-builder-handler) is a great way to build a complex nested command
+line application; in a nutshell, it allows you to decompose your
+command line application into individual commands, helping with the
+separation of concerns:
+
+<pre><code class="hljs language-javascript">require('yargs')
+  .command('foo', 'foo command', function (yargs) {
+    // builder function, receives a yargs instance
+    // which you can use to add command-specific options.
+  }, function (argv) {
+    // handler function, called once parsing is complete.
+    console.log('foo')
+  })
+  .command('bar', 'bar command', {}, function (argv) {
+    console.log('bar')
+  })
+  .argv</code></pre>
+
+**slick!**
+
+Commands are one of yargs' most complex features, and we continue
+to iterate on their API; we've made the following command-related breaking changes
+in this release:
+
+* **[default help command added](https://github.com/yargs/yargs/pull/574)**: you can now
+  simply type `./cli.js help`, to receive yargs' help output.
+* **[changes to `demand()`](https://github.com/yargs/yargs/pull/582)**: `demand()` now properly
+  handles being invoked relative to a command; before this fix, the command itself would cause
+  constraints to be applied incorrectly.
+* **[`builder` no longer requires yargs to be returned](https://github.com/yargs/yargs/pull/549)**: The third
+  argument to `command` is a builder for describing options specific to the command. The builder command no longer requires that you
+  return a yargs instance. Simply interact with the yargs instance passed as the first argument, and your options
+  will take effect.
+* **[`builder` now defaults to noop builder](https://github.com/yargs/yargs/pull/583)**: the builder
+  now resets all yargs configuration settings that are not flagged as being [`global`](https://github.com/yargs/yargs#globalglobals).
+* **[global `fail`](https://github.com/yargs/yargs/pull/583)**: the `fail()` method now applies globally. This means that
+  you can define a `fail()` handler once on the top-level yargs object, and nested failures in commands will bubble up to it.
+
+### Tweaks to Parser
+
+[yargs-parser](https://github.com/yargs/yargs-parser) is the underlying engine that
+processes the strings passed into  [`process.argv`](https://nodejs.org/docs/latest/api/process.html#process_process_argv).
+
+We've made a couple breaking changes to the parser in this release:
+
+* **[we now handle negative numbers](https://github.com/yargs/yargs-parser/pull/44)**: prior to
+  this release negative numbers were interpreted as numeric options, with this
+  release you can now pass negative numbers as values to options: `-number -123`.
+* **[fixes to option groups](https://github.com/yargs/yargs-parser/pull/19)**: a bug has been
+  fixed with option groups (`-abc`) terminated by numeric values (`-abc123`).
+
+### Miscellaneous
+
+* **[fixed name of Chinese locale](https://github.com/yargs/yargs/pull/511)**: we've renamed
+  zh.json to zh_CN.json
+
+## What's Next
+
+The biggest thing currently on the core team's mind is documentation. The [yargs README](https://github.com/yargs/yargs) has grown unwieldy! we have some plans in the
+works to help solve this problem:
+
+* over the next few months expect to see targeted tutorials popping up on the yargs
+  website; the first of which will likely be on the topic of commands.
+* we've also created a [gitter.im chatroom](https://gitter.im/yargs/Lobby?utm_source=share-link&utm_medium=link&utm_campaign=share-link) where folks can get help using yargs from its core contributors.
+
+Hope you enjoy all the exciting updates in yargs 5.0.0!
+
+-- [Ben](https://github.com/bcoe).
+</div>
+
+{::options parse_block_html="true" /}
+<div class="page-box right">
+
+## We got stickers!
+
+[![Yargs Sticker](/images/yargs-laptop-hexagon.png)](https://www.stickermule.com/marketplace/tags/yargs)
+
+Order on [StickerMule](https://www.stickermule.com/marketplace/tags/yargs).
+
+</div>
+</div>