Question

I have a slideshow web application that for some slides include a beforeSlideshowAction that is rendered from serverside together with that slide, the javascript is rendered together with the contents of that slide since it is part of a slide-template generating this content.

However, the javascript functions as of below is not updated together with my content. For example, if I were to load the slideshow, then switch places on these two slides (which update will be done by ajax after the slideshow has ran a full cycle), the beforeSlideshowAction_slide1() as of below will now be rendered as beforeSlideshowAction_slide2(), but when called, there will only exist a function called beforeSlideshowAction_slide1(), I assume all javascript function are registered upon page initial load only.

I remember solving a similar issue another time by calling eval on the script block containing the updated function, is there a less hackish solution to my problem?

{# comment: from here the document will be updated by Ajax #}
<div id="slideshowbody">

    {# comment: ordernumber is now 1 #}
    <div id="slide{{ ordernumber }}">

        //some content goes here

        <script>
        function beforeSlideshowAction_slide{{ ordernumber }}() {

            //assign appropriate value to videoContent for current slide
            videoContent[{{ ordernumber }}]='video={{ data0 }}&height={{ data1 }}&width={{ data2 }}&codec={{ data3 }}&fullscreen={{ data5 }}';

        }
        </script>

    </div>


    {# comment: ordernumber is now 2 #}
    <div id="slide{{ ordernumber }}">

        //some content goes here

        //slide 2 doesn't have a function for a "beforeSlideshowAction"

    </div>

</div>

Don’t worry that I might be calling a function that doesn’t exist, I do it in a try/catch block, I have set it up so that a beforeSlideshowFunction is called for each slide in a try/catch, and in the slide-template I just define a function there if I want one, if not I just skip it.

Answer 1

Here is how I ended up solving it

<script id="beforeSlideshowAction{{ ordernumber }}_script" type='text/javascript'>

//define the function for later use (page updates)
window.beforeSlideshowAction_slide{{ ordernumber }} = function() {  

    console.log('runnin beforeSlideshowAction for slide {{ ordernumber }}');

    //assign appropriate value to videoContent for current slide
    videoContent[{{ ordernumber }}]='video={{ data0 }}&height={{ data1 }}&width={{ data2 }}&codec={{ data3 }}&fullscreen={{ data5 }}';

}

//run
var x = window['beforeSlideshowAction_slide{{ ordernumber }}'];
x();

</script>

…and later on, when this has been changed by ajax and the slide1 function might instead be the slide3-function…

            //replace the innerHTML of body with the new stuff
            document.getElementById('slideshow_body').innerHTML=newContent;


            //update the videoContents and run other beforeSlideshow-actions
            for (var i=1;i<(pauseTimes.length+1);i++)
            { 

                try {
                    console.log('slide '+i+' action...');

                    //set previous version of beforeSlideshowAction i to null
                    window['beforeSlideshowAction_slide'+i] = null;

                    //define it anew (will this run it too?)
                    ie_compatible_eval( document.getElementById('beforeSlideshowAction'+i+'_script').innerHTML )

                }
                catch(e) {
                    console.log('slide '+i+' none');
                    //do nothing since we will not have a function named that for every slide, error is expected
                }

            }