Question

I need to use insertRule to modify some CSS via Javascript. I also need to support IE7-8, so I need some way to differentiate in Javascript whether I should use insertRule or addRule (without browser sniffing).

This is what I’m trying and it does not work:

var sheets = document.styleSheets   
if(sheets.insertRule) {
    alert("insert");
    // insert 
} else {
    alert("add");
    // add
}

Any idea if this is possible and how to get it to work?

EDIT:
If I run this in IE8, I get an error on the page object does not support this property or method

Answer 1

There seem to be no bugs in IE8, as evidenced by this test run.

var sheets = document.styleSheets   
if(sheets.insertRule) {
    alert("insert");
    // insert
} else {
    alert("add");
    // add
}

The problem is probably due to the fact that the code you have replaced with comments calls methods that are undefined.