var origText = '';

function findinpage(id) 
{    
    if(origText.length == 0)
    {
         origText = document.getElementById('content').innerHTML;
    }
    var div = document.getElementById('content');
    var textbox = document.getElementById(id);         
    var txttofind = textbox.value;
    if(txttofind.length < 4)
    {
        alert('Search text must be more than 3 characters.');
        return false;
    }
    
    div.innerHTML = origText;
    div.innerHTML = div.innerHTML.replace(eval('/'+txttofind+'/gi'), '<span style="background:yellow;">' + txttofind + '</span>');
    if(div.innerHTML == origText)
    {
        alert('Your search text does not appear in this document.');
    }
    return false;
}