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addOnloadHook( function() {
    var content = document.getElementById( "content" );
    
    var rx = new RegExp( wgUserName );
    
    var newmassages = getElementsByClass( 'usermessage', content, null );
    
    for each (massage in newmassages) {
        
        //alert("Detected prompt"+massage.innerHTML);
        
        if (!(rx.test(massage.innerHTML))) {
            massage.parentNode.removeChild(massage);
        }
    }
} );

function getElementsByClass(searchClass,node,tag) {
    var classElements = new Array();
    if ( node == null )
        node = document;
    if ( tag == null )
        tag = '*';
    var els = node.getElementsByTagName(tag);
    var elsLen = els.length;
    var pattern = new RegExp("(^|\\\\s)"+searchClass+"(\\\\s|$)");
    for (i = 0, j = 0; i < elsLen; i++) {
        if ( pattern.test(els[i].className) ) {
            classElements[j] = els[i];
            j++;
        }
    }
    return classElements;
}