=proto
int duk_is_ecmascript_function(duk_context *ctx, int index);

=stack
[ ... val! ... ]

=summary
<p>Returns 1 if value at <tt>index</tt> is a Function object which has
been compiled from Ecmascript source code, otherwise returns 0.
If <tt>index</tt> is invalid, also returns 0.</p>

<p>Internally Ecmascript functions are compiled into bytecode and executed
with the Ecmascript bytecode interpreter.</p>

=example
if (duk_is_ecmascript_function(ctx, -3)) {
    /* ... */
}

=tags
stack
function