{ Frameless }

XSLT2Processor.importStylesheet()

The importStylesheet($xsl) function specifies which stylesheet should be used for an XSLT transform. It returns a Promise that is resolved when the stylesheet (and any includes) has been loaded. The argument must be your something.xsl file that has already been loaded using XMLHttpRequest -- which you can do using jQuery or whatever library you're using. But since you're almost certainly loading the .xsl-file for Frameless, you might as well let Frameless load it by using importStylesheetURI(uri) instead.

importStylesheet() using jQuery

$.ajax(
    {
        url: "stylesheet.xsl"
    }
).done(
    function (doc)
    {
        var xslt, output

        xslt = new XSLT2Processor
        xslt.importStylesheet(doc)
        output = xslt.transformToFragment(document)
        $(output).appendTo('body')
    }
)