Javascript - Truncate text after certain number of charecters

Here is the peice of javascript code which can be used to truncate all the texts in a HTML page after certain number of charecters:

function truncateText(tagid, size)     
{        
    var allTdElements = document.getElementsByTagName('td');        
    for(var j=0; j < allTdElements.length ; j++)      
    {              
        var tempTdData = '';        
        var lineSeparator = '<BR>';        
        if (allTdElements[j].id == tagid)        
        {         
            var tdData = allTdElements[j].childNodes[0].innerHTML;        
            var arrayOfStrings = tdData.split(lineSeparator);     
            
            for (var k=0; k < arrayOfStrings.length; k++)      
            {      
                if(arrayOfStrings[k].length > size)      
                {        
                    if(tempTdData.length > 0)
                        tempTdData += lineSeparator + arrayOfStrings[k].substr(0,size) + '...';  
                    else
                        tempTdData += arrayOfStrings[k].substr(0,size) + '...';
                }      
                else      
                {      
                    if(tempTdData.length > 0)        
                        tempTdData += lineSeparator + arrayOfStrings[k].substr(0,size);        
                    else        
                        tempTdData = tempTdData + arrayOfStrings[k].substr(0,size);      
                }
            }                  

            allTdElements[j].childNodes[0].innerHTML = tempTdData;        
        }      
    }     
}