<h2>Array.prototype.concat() trailing non-existent elements</h2>

<p>When the result of an array <code>concat()</code> would have trailing non-existent

elements, the standard behavior is to ignore them so that they are not reflected in

the result <code>length</code>. Real world behavior is to include them in the result

value <code>length</code>. See

<a href="https://github.com/svaarala/duktape/blob/master/tests/ecmascript/test-bi-array-proto-concat-nonstd-trailing.js">test-bi-array-proto-concat-nonstd-trailing.js</a>.</p>

<p>The real world behavior seems consistent in other engines (V8, Rhino, Spidermonkey

at least), so Duktape uses the real world behavior by default. The strict standards compliant

behavior can be enabled by disabling the config option <code>DUK_USE_NONSTD_ARRAY_CONCAT_TRAILER</code>.</p>

<h2>Array.prototype.map() trailing non-existent elements</h2>

<p>Similar issue as with <code>Array.prototype.concat()</code>, see

<a href="https://github.com/svaarala/duktape/blob/master/tests/ecmascript/test-bi-array-proto-map-nonstd-trailing.js">test-bi-array-proto-map-nonstd-trailing.js</a>. The strict standards compliant behavior can be

enabled by disabling the config option <code>DUK_USE_NONSTD_ARRAY_MAP_TRAILER</code>.</p>