Saxon » SaxonJS

The specification of ixsl:call at https://www.saxonica.com/saxon-js/documentation2/index.html#!ixsl-extension/functions/call says

See Type Conversion for details on how the supplied parameters in $arguments are converted from XDM to JavaScript, and how any returned JavaScript objects are converted to XDM.

I believe that no conversion is applied to the $object and $method arguments of ixsl:call, only to the values supplied in $arguments.

Hmm, okay. Any workarounds for this then?

It rather depends on what you are trying to achieve, which isn't clear. What's wrong with array:append()?

I would discourage any attempt to modify an XDM array in-situ. Saxon is going to assume that the contents of a variable remain unchanged once bound, and any attempt to subvert that is going to have very unpredictable consequences. I think that the conversion rules mean you'll normally get a copy of the array anyway.

There is still something weird going on, if not with array conversion then with ixsl:set-property in combination with arrays.

<xsl:variable name="js-array" select="ixsl:eval('Array(1, 2)')"/>
<xsl:value-of select="ixsl:call(ixsl:get(ixsl:window(), 'Array'), 'isArray', [ $js-array ])"/> <!-- true -->
<xsl:value-of select="ixsl:call(ixsl:get(ixsl:window(), 'JSON'), 'stringify', [ $js-array ])"/> <!-- [1, 2] -->

<ixsl:set-property name="prop" select="$js-array"/>
<xsl:value-of select="ixsl:call(ixsl:get(ixsl:window(), 'Array'), 'isArray', [ ixsl:get(ixsl:window(), 'prop') ])"/> <!-- false -->
<xsl:value-of select="ixsl:call(ixsl:get(ixsl:window(), 'JSON'), 'stringify', [ ixsl:get(ixsl:window(), 'prop') ])"/> <!-- 1 -->

This test case shows that $js-array is an array as expected, but after it's been set as the value of window.prop, it's not an array anymore.

I think Mike is right about the attempt to call push on an XDM array. The first argument to ixsl:call is expected to be a (native) JavaScript object.

The ixsl:set-property problem is trickier. It feels like that should work, and I have managed to make it work, but I'm not sure I like my workaround.