How to get the current active text within a scrolled DIV

Question

A chipped DIV containing paragraphs that need a scrollbar

e.g.

<div id="text" style='overflow:scroll;width:200px;height:200px'>

<div style='font-size:64px;'>BIG TEXT</div> 
Lorem Ipsum is simply dummy text of the printing and typesetting 
industry. Lorem Ipsum    has been the industry's standard dummy text ever  
since the 1500s, when an unknown printer took a galley of type and scrambled it 
to make a type specimen book. It has survived not only five centuries, but also 
the leap into electronic typesetting, remaining essentially unchanged.
It was popularised in the 1960s with the release of Letraset sheets 
containing Lorem Ipsum passages, and more recently with desktop publishing software 
like Aldus PageMaker 
including versions of Lorem Ipsum.

</div>

When the scrollbar move, the text change (due to overflow:scroll), is it possible to select only the text displayed in the current view port?

Example: http://jsfiddle.net/cxgkY/15/

Updated: The inner HTML might contains variable sized text

Answer 1

Here's a little demo that should do what you're expecting: little link (works with variable sizes as well). The idea is to automatically create a separate span for each word, and then, each time the div is scrolled, check which spans are visible (by checking their top offset), thus updating document selection range. If anything isn't clear I'd be glad to explain it.

Answer 2

Not sure what you mean by selecting just the text in the current viewport, but maybe something like this:

var elm = $("#text"),
    t = $(elm).text().split(' '),
    html = [],
    selected_text = '';

$.each(t, function(i,e) {
    html.push('<span>'+e+'</span>');
});

elm.html(html.join(' '));

$('span', elm).each(function(i,e) {
    if ($(e).offset().top < elm.height()) {
        $(e).css('background', 'red');
        selected_text += $(e).text()+' ';
    }
});

FIDDLE

If the point of this exercise is to just display the text in another container element you can just do it the regular way and fake it:

$("#text").on('scroll', function() {
    $('#visible').html($(this).html()).scrollTop($(this).scrollTop());
});

FIDDLE ​