Question

I’m comparing all iframes in my javascript, to see if one of them matches my element’s (an a -tag) body element. The problem I have is that the collection of iframes can sometimes change, because they are all generated by a framework. Hence sometimes I get “Access is denied” errors in IE8 and sometimes I don’t. I’m not referencing any external Iframes since all my Iframe are part of the framework and hence have same protocoll, port etc. This is the code I use to loop through the iframe collection:

var calculatedwidth = 0;
var calculatedheight = 0;

var searchbody = $(srcElement).closest('body');
//I store the Iframe-nodelist in var arrFrames
var arrFrames = document.getElementsByTagName("iframe");
LabelA1:
for(i = 0; i<arrFrames.length; i++){
    //console.log(i);
    //if(arrFrames[i].id != 'PeopleDetailsIframe'){

        if($(arrFrames[i].contentWindow.document.body).is(searchbody)){
        // This line is where the error occures normaly
               calculatedwidth = $(arrFrames[i]).offset().left;
               calculatedheight = $(arrFrames[i]).offset().top;
               break LabelA1;
        }
        else{
              //console.log("Forum Iframe not found");
            }
     }  
}  

I temporarily fixed my problem by including a break, to break out of the loop if my searched iframe is found. This works about 80% of the time my code is executed. But since the webpage is customizable, some users have responded that they get a javascript error when my code runs. Based on some research I did on the subject Cross-Domain scripting , Scripting with Iframe Collection, I learned that the Iframe collection is a live-collection? So this means that the collection is bound to change (sometimes) when I’m looping through it. So I assumed that this can cause 2 errors, an infinite loop or wrong index errors. I thought that storing the refrence to the iframes in a var, would prevent the errors. But obviously I was wrong:

var arrFrames = document.getElementsByTagName("iframe");

This didn’t help. Any suggestions how I can prevent the wrong index Issue? Or am I completely wrong about where my problem lies?
Help is much appreciated!

Answer 1

You can put a try-catch around the if(). That way the loop should always run without an error.

var calculatedwidth = 0;
var calculatedheight = 0;

var searchbody = $(IframeDocument).closest('body');
var arrFrames = document.getElementsByTagName("iframe");
LabelA1:
for(i = 0; i<arrFrames.length; i++){
    //console.log(i);
    //if(arrFrames[i].id != 'PeopleDetailsIframe'){

        try {
            if($(arrFrames[i].contentWindow.document.body).is(searchbody)){
            // This line is where my the error occures normaly
                   calculatedwidth = $(arrFrames[i]).offset().left;
                   calculatedheight = $(arrFrames[i]).offset().top;
                   break LabelA1;
            }
            else{
                  //console.log("Forum Iframe not found");
                }
        } catch() {
            // the IFrame has security issue => avoid it
        }
     }  
}