Why a pop-up alert can affect “designMode”?

StackOverflow https://stackoverflow.com/questions/741343

Question

I was expreimenting to build a page editor. One issue just drove me crazy in firefox.

The page code is below:

<body>
<iframe WIDTH=200 HEIGHT=200 id="myEditor"></iframe>
<script>

    function getIFrameDocument(sID){
        // if contentDocument exists, W3C compliant (Mozilla)
        if (document.getElementById(sID).contentDocument){
            alert("mozilla"); // comment out this line and it doesn't work
            return document.getElementById(sID).contentDocument;
        } else {
            // IE
            alert("IE");
            //return document.getElementById(sID);
            return document.frames[sID].document;
        }
    }

    getIFrameDocument("myEditor").designMode = "On";

</script>

</body>

It just check whether it is approprate to set "designMode" in Mozilla way or IE way. When the page loads, a "Mozilla" pops up; click the iframe area, and the focus is on the iframe and I can input with keyboard.

This looks fine, but when I comment out the line “alert("mozilla");”， it doesnt work. The "designMode" is "Off" as FireBug shows.

This is so wired. Why a alert can affect the DOM and javascript? BTW, my Firefox is 3.0.6.

Was it helpful?

Solution

Because the alert gives the iframe time to load. You should set designMode to "on" only after the iframe document has loaded:

iframe.onload = function() {
    doc.designMode = "on";
};
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