Yes:<p>for each (...) -&gt; It&#x27;s not supported anywhere, so forget it.<p>for (var x in a) -&gt; x is the key, so it&#x27;s kind of inconvenient. You have to watch out for inherited properties&#x2F;methods so one should check for a.hasOwnProperty(x).<p>for (var x of a) -&gt; It has mostly no gotchas. Only poor browser support.<p>.forEach only works with arrays and from ES5 on. You have the good old &quot;this&quot;&#x2F;scope gotcha.