<p dir="auto"><strong>I'm submitting a</strong></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="[x] bug report =&gt; search github for a similar issue or PR before submitting
[x] feature request
[ ] support request =&gt; Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question"><pre class="notranslate"><code class="notranslate">[x] bug report =&gt; search github for a similar issue or PR before submitting
[x] feature request
[ ] support request =&gt; Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question
</code></pre></div>
<p dir="auto"><strong>Current behavior</strong></p>

<p dir="auto">Not sure if this is a bug or a feature request, but <a href="mailto:radokirov@google.com">radokirov@google.com</a> suggested me to file an issue.<br>
When there is a list of primitives, let say booleans <code class="notranslate">let list: Array&lt;boolean&gt; = [true, true, false, true]</code>, *ngFor is not capable to track it correctly. It's clear from documentation, that it is required to use some tracking function, but it looks overkilled to implement a tracking function that looks like this:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="track(i: number): number {
  return i;
}"><pre class="notranslate"><code class="notranslate">track(i: number): number {
  return i;
}
</code></pre></div>
<p dir="auto"><strong>Expected behavior</strong></p>

<p dir="auto">Is it possible to add a predefined variable <code class="notranslate">index</code> as a tracking parameter?<br>
<code class="notranslate">*ngFor="let item of list; let i = index; trackBy: index"</code></p>
<p dir="auto"><strong>Minimal reproduction of the problem with instructions</strong></p>

<p dir="auto"><a href="https://plnkr.co/edit/I1MP9vMfDyC9jdCgJCe0?p=preview" rel="nofollow">https://plnkr.co/edit/I1MP9vMfDyC9jdCgJCe0?p=preview</a></p>
<p dir="auto"><strong>What is the motivation / use case for changing the behavior?</strong><br>
Get rid of unnecessary tracking function.</p>
<p dir="auto"><strong>Please tell us about your environment:</strong> Goobuntu, Cider</p>
<ul dir="auto">
<li><strong>Angular version:</strong> 2.2.1</li>
<li><strong>Browser:</strong>  Chrome 55.0.2883.87 (64-bit)</li>
<li><strong>Language:</strong> TypeScript</li>
</ul>
<p dir="auto">Helps manual debugging</p>