Topic: document.write == "evil"

I'm quite sure that document.write is an evil Javascript command. But I need more evidence to back this up. Does anyone else hate this command?



- AIM: MASKKKK

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Interesting timing: earlier this week I made myself a wrapper for document.write and document.writeln. See below if you're interested.

I've not tried to collect stats or anything but at first glance the use cases are:

• Google analytics and other stats/tracking tools
• building SCRIPT tags pointing to affiliate/ads programs
• building IFRAMEs with ads
• building OBJECTs with ads in Flash
• building NOSCRIPT tags!!!
• stupid calendar widgets
• adding a A tag with a mailto: address

So far I don't feel like I'm missing much.

/**
 *  wrapper for document.write and document.writeln
 */
(function()
{
    var _buffer     = '';
    var _timeout    = 0;
    var _emitter    = window.opera?opera.postError:window.console?console.log:alert;

    
    document.writeln=document.write=function()
    {
        //  the replace simply adds a \n after each closing tag
        _buffer += arguments.join('').replace( /(<\/[^>]+>|\/>)/g, '$1\n' );
        clearTimeout( _timeout );
        _timeout = setTimeout( _dump, 100 );
    }
    
    function _dump()
    {
        if( _buffer!=='' )
        {
            _emitter( 'document.write - '+ location.href +'\n \n'+ _buffer );
            _buffer = '';
        }
    }
    
})();

Yeah I can't argue with that, but I think it depends on how you use it.

If it's in scattered snippets throughout a large page; wouldn't it be easier to read if using an onload or jQuery's $(document).ready(function {}); and then use dom functions that get id's and add nodes to them?

If you're script is being planned to be used someone else's page, like you're examples above it seems to make more sense.



- AIM: MASKKKK

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document.write is an antique and lightweight method. It works even before the DOM is ready. Also it has no dependencies on the user agent implementing DOM 1+ or on a JS framework. This thing works eeeeverywhere and right away ... even in antique browsers. Oh and document.write does NOT block the user agent from loading other resources.



(Edited by poi on 11-06-2009 10:24)