javascript.html


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			<meta name="dcterms.date" content="2018-09-21" />
			<title>Style Guide</title>
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		<h1>Style Guide</h1>
				<p class="subtitle">Software Engineering at Driver</p>
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	    This guide recommends stylistic and architectural best
	    practices, designed to make your code easier for others to
	    understand. It offers <em>guidelines</em> not <em>rules</em>,
	    and there are situations in which the advice offered
	    should be actively ignored.
	    <hr>
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	<main class="container">
	    <h2 id="javascript">JavaScript</h2>
<ul>
<li><p>Type with flow</p></li>
<li><p>Style with <a href="https://prettier.io/">prettier</a> (<a href="#prettier">see section below</a>)</p></li>
<li><p>Lint with eslint and use <code>eslint:recommended</code> at a minimum</p></li>
<li><p>Test with <a href="https://facebook.github.io/jest/">jest</a> and enzyme</p></li>
<li><p>2 spaces (instead of tabs)</p></li>
<li><p>Promises (not callbacks)</p></li>
<li><p>No <a href="https://medium.com/google-developers/exploring-es7-decorators-76ecb65fb841">decorators</a></p></li>
<li><p>No <a href="https://mobx.js.org/">mobx</a></p></li>
<li><p>Place tests alongside the file(s) it tests (not in a separate directory)</p></li>
<li><p>End test files with <code>.test.js</code></p></li>
</ul>
<h3 id="reactredux">React/Redux</h3>
<ul>
<li><p>Lint with <a href="https://github.com/palantir/tslint-react"><code>tslint-react</code></a> or eslint’s <a href="https://github.com/yannickcr/eslint-plugin-react"><code>plugin:react/recommended</code></a> at a minimum.</p></li>
<li><p>No unnecessary and empty <code>&lt;div&gt;</code>’s</p></li>
<li><p>If <code>this.props.&lt;variable name&gt;</code> is used more than once, dereference it at the top of <code>render</code>.</p></li>
<li><p>Extract variables used in <code>render()</code> to the top of <code>render()</code></p></li>
<li><p>API calls should lie in a testable file outside of components.</p></li>
<li><p>Components should not wait for promises to resolve, instead listen on props via redux’ <code>mapStateToProps()</code>.</p></li>
<li><p>Declare and export components in separate places (otherwise the web inspector cannot name components properly)</p></li>
</ul>
<h3 id="flowtype">Flowtype</h3>
<ul>
<li><p>Any types used in more than one file should be placed in <code>src/types.js</code></p></li>
<li><p>Add flow linting via <a href="https://github.com/gajus/eslint-plugin-flowtype">eslint-plugin-flowtype</a></p></li>
<li><p>Disallow “<code>any</code>” with <a href="https://github.com/gajus/eslint-plugin-flowtype#no-weak-types">eslint no-weak-types</a> (use “<code>Obect</code>” and “<code>Function</code>” to cover complicated use-cases)</p></li>
<li><p>In components which use <code>mapStateToProps</code>, separate <code>OwnProps</code> from <code>ConnectedProps</code> into separate types. Join them with <code>type Props = OwnProps &amp; ConnectedProps</code>. In addition, if using <code>mapDispatchToProps</code>, create a type <code>DispatchProps</code> and join that with <code>Props</code>.</p></li>
</ul>
<h3 id="𝓣𝓢-typescript-𝓣𝓢">𝓣𝓢 TypeScript 𝓣𝓢</h3>
<ul>
<li><p>Lint with <a href="https://github.com/palantir/tslint"><code>tslint:recommended</code></a> at a minimum.</p></li>
<li><p>No implicit any (type everything that’s not inferable)</p></li>
<li><p>Any variable declared without an initial value should be typed</p></li>
</ul>
<h3 id="prettier">Prettier</h3>
<p>Add the following to <code>package.json</code>:</p>
<div class="sourceCode" id="cb1"><pre class="sourceCode json"><code class="sourceCode json"><a class="sourceLine" id="cb1-1" data-line-number="1">  <span class="er">&quot;prettier&quot;:</span> <span class="fu">{</span></a>
<a class="sourceLine" id="cb1-2" data-line-number="2">    <span class="dt">&quot;overrides&quot;</span><span class="fu">:</span> <span class="ot">[</span></a>
<a class="sourceLine" id="cb1-3" data-line-number="3">      <span class="fu">{</span></a>
<a class="sourceLine" id="cb1-4" data-line-number="4">        <span class="dt">&quot;files&quot;</span><span class="fu">:</span> <span class="ot">[</span><span class="st">&quot;*.js&quot;</span><span class="ot">,</span> <span class="st">&quot;*.scss&quot;</span><span class="ot">,</span> <span class="st">&quot;*.css&quot;</span><span class="ot">,</span> <span class="st">&quot;*.pcss&quot;</span><span class="ot">]</span><span class="fu">,</span></a>
<a class="sourceLine" id="cb1-5" data-line-number="5">        <span class="dt">&quot;options&quot;</span><span class="fu">:</span> <span class="fu">{</span></a>
<a class="sourceLine" id="cb1-6" data-line-number="6">          <span class="dt">&quot;singleQuote&quot;</span><span class="fu">:</span> <span class="kw">true</span><span class="fu">,</span></a>
<a class="sourceLine" id="cb1-7" data-line-number="7">          <span class="dt">&quot;trailingComma&quot;</span><span class="fu">:</span> <span class="st">&quot;all&quot;</span></a>
<a class="sourceLine" id="cb1-8" data-line-number="8">        <span class="fu">}</span></a>
<a class="sourceLine" id="cb1-9" data-line-number="9">      <span class="fu">}</span></a>
<a class="sourceLine" id="cb1-10" data-line-number="10">    <span class="ot">]</span></a>
<a class="sourceLine" id="cb1-11" data-line-number="11">  <span class="fu">}</span></a></code></pre></div>
<p>The following information about prettier is better described on the prettier documentation <a href="https://prettier.io/docs/en/precommit.html#option-1-lint-staged-https-githubcom-okonet-lint-staged">here</a>. Use <code>lint-staged</code> to auto-call prettier in a <code>precommit</code> “<code>script</code>”:</p>
<div class="sourceCode" id="cb2"><pre class="sourceCode json"><code class="sourceCode json"><a class="sourceLine" id="cb2-1" data-line-number="1">  <span class="er">&quot;lint-staged&quot;:</span> <span class="fu">{</span></a>
<a class="sourceLine" id="cb2-2" data-line-number="2">    <span class="dt">&quot;src/**/*.scss&quot;</span><span class="fu">:</span> <span class="ot">[</span><span class="st">&quot;prettier --parser scss --write&quot;</span><span class="ot">,</span> <span class="st">&quot;git add&quot;</span><span class="ot">]</span><span class="fu">,</span></a>
<a class="sourceLine" id="cb2-3" data-line-number="3">    <span class="dt">&quot;src/**/*.{js,css}&quot;</span><span class="fu">:</span> <span class="ot">[</span><span class="st">&quot;prettier --parser flow --write&quot;</span><span class="ot">,</span> <span class="st">&quot;git add&quot;</span><span class="ot">]</span><span class="fu">,</span></a>
<a class="sourceLine" id="cb2-4" data-line-number="4">    <span class="dt">&quot;nightwatch/**/*.js&quot;</span><span class="fu">:</span> <span class="ot">[</span><span class="st">&quot;prettier --write&quot;</span><span class="ot">,</span> <span class="st">&quot;git add&quot;</span><span class="ot">]</span></a>
<a class="sourceLine" id="cb2-5" data-line-number="5">  <span class="fu">}</span></a></code></pre></div>
<h3 id="npm">Npm</h3>
<ul>
<li>Support the following <code>script</code>’s in your root <code>package.json</code>:</li>
</ul>
<ol type="1">
<li><code>“watch”</code>: Starts the dev server</li>
<li><code>“build”</code>: Builds static assets (if they exist) “<code>/src</code>” -&gt; “<code>/build</code>”</li>
<li><code>“test”</code>: Runs all tests (linting first, then unit tests)</li>
</ol>
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	    	    <span class="date">2018-09-21</span>
	    	    	    | <a href="https://github.com/drivergroup/best-practices/blob/master/guides/javascript.md" style="display: inline-block;"><i class="fa fa-github"></i> Edit on GitHub</a>
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