<p>ExtJS has Ext.each() function, but is there a map() also hidden somewhere?</p>

<p>I have tried hard, but haven't found anything that could fill this role. It seems to be something simple and trivial, that a JS library so large as Ext clearly must have.</p>

<p>Or when Ext really doesn't include it, what would be the best way to add it to Ext. Sure, I could just write:</p>

<pre><code>Ext.map = function(arr, f) { ... };
</code></pre>

<p>But is this really the correct way to do this?</p>

Since
```
map
```
is more of a utility than anything, I don't see why there would be any special way of plugging it into the Ext namespace; the way you propose would work well enough, though you might want to do it thusly:
```
```
if(Ext && typeof(Ext.map) == "undefined") { // only if Ext exists & map isn't already defined
   Ext.map = function(arr, f) { ... };
}
```
```
Seems like that would be fine...but then, I don't use ExtJS, so I don't know. I did take a gander at their docs and it doesn't seem like there is anything special to do in this case.