<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have searched the <a href="https://github.com/zeit/next.js/issues?q=is%3Aissue">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h2 dir="auto">Expected Behavior</h2>


<p dir="auto">App should work after upgrading to Next v5.1.0. in <a class="issue-link js-issue-link notranslate" rel="noopener noreferrer nofollow" href="https://linear.app/vercel/issue/NEXT-js">Next-js</a> supported browsers.</p>
<h2 dir="auto">Current Behavior</h2>


<p dir="auto">Noticed <code class="notranslate"> 'Symbol' is undefined</code> issue in IE11 after upgrading to Next v5.1.0. We don't see this issue with Next v4.x.</p>
<h2 dir="auto">Steps to Reproduce (for bugs)</h2>


<ol dir="auto">
<li>Upgrade app, which has for-of loop in its source code, to Nextv5.1.0.</li>
<li>Open the application in IE 11 after build process and check the dev console.</li>
</ol>
<h2 dir="auto">Context</h2>


<p dir="auto">This is happening with Next v5.1.0.</p>
<p dir="auto">Code generated for <code class="notranslate">for-of</code> loop with Next v5.1.0</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="for (var g = l[Symbol.iterator](), w; !(h = (w = g.next()).done); h = true) {                        
}"><pre class="notranslate"><code class="notranslate">for (var g = l[Symbol.iterator](), w; !(h = (w = g.next()).done); h = true) {                        
}
</code></pre></div>
<p dir="auto">Next v4.x version with same source code.</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="for (var h, g = (0,r.default)(l); !(y = (h = g.next()).done); y = !0) {
}"><pre class="notranslate"><code class="notranslate">for (var h, g = (0,r.default)(l); !(y = (h = g.next()).done); y = !0) {
}
</code></pre></div>
<p dir="auto">We can fix the issue by adding <code class="notranslate">babel-polyfill</code> or <code class="notranslate">babel runtime-transform</code> to our code but it would be consistent if we have a solution as part of Next build.</p>
<h2 dir="auto">Your Environment</h2>

<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>next</td>
<td>5.1.0</td>
</tr>
<tr>
<td>node</td>
<td>8.11.1</td>
</tr>
<tr>
<td>OS</td>
<td>windows</td>
</tr>
<tr>
<td>browser</td>
<td>IE 11</td>
</tr>
<tr>
<td>etc</td>
<td></td>
</tr>
</tbody>
</table>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/10725504/39061558-49b228c8-448a-11e8-9fc9-6a79f3c90e22.png"><img width="1075" alt="screen shot 2018-04-20 at 9 51 03 am" src="https://user-images.githubusercontent.com/10725504/39061558-49b228c8-448a-11e8-9fc9-6a79f3c90e22.png" style="max-width: 100%;"></a></p>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have searched the <a href="https://github.com/zeit/next.js/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h2 dir="auto">Expected Behavior</h2>


<h2 dir="auto">Current Behavior</h2>


<h2 dir="auto">Steps to Reproduce (for bugs)</h2>


<ol dir="auto">
<li></li>
<li></li>
<li></li>
<li></li>
</ol>
<h2 dir="auto">Context</h2>


<h2 dir="auto">Your Environment</h2>

<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>next</td>
<td></td>
</tr>
<tr>
<td>node</td>
<td></td>
</tr>
<tr>
<td>OS</td>
<td></td>
</tr>
<tr>
<td>browser</td>
<td></td>
</tr>
<tr>
<td>etc</td>
<td></td>
</tr>
</tbody>
</table>