I have a textarea with lots and lots of text:
<textarea cols="50" rows="10" id="txt">lots and lots of text goes here</textarea>
I want to scroll the textarea down, so the user can see 2000-th character. How can I do this using javasctipt/jQuery?
$('#txt').scrollToCharNo(2000); // something like this would be great
EDIT (my solution)
Well, I managed to make it work myself. The only way I found, is to create a DIV with the same font and width as the textarea, put a SPAN near the needed character and find the position of that span.
I am sure, that somebody might find my solution useful, so i'll paste it here:
jQuery.fn.scrollToText = function(search) {
// getting given textarea contents
var 开发者_运维问答text = $(this).text();
// number of charecter we want to show
var charNo = text.indexOf(search);
// this SPAN will allow up to determine given charecter position
var anch = '<span id="anch"></span>';
// inserting it after the character into the text
text = text.substring(0, charNo) + anch + text.substring(charNo);
// creating a DIV that is an exact copy of textarea
var copyDiv = $('<div></div>')
.append(text.replace(/\n/g, '<br />')) // making newlines look the same
.css('width', $(this).attr('clientWidth')) // width without scrollbar
.css('font-size', $(this).css('font-size'))
.css('font-family', $(this).css('font-family'))
.css('padding', $(this).css('padding'));
// inserting new div after textarea - this is needed beacuse .position() wont work on invisible elements
copyDiv.insertAfter($(this));
// what is the position on SPAN relative to parent DIV?
var pos = copyDiv.find('SPAN#anch').offset().top - copyDiv.find('SPAN#anch').closest('DIV').offset().top;
// the text we are interested in should be at the middle of textearea when scrolling is done
pos = pos - Math.round($(this).attr('clientHeight') / 2);
// now, we know where to scroll!
$(this).scrollTop(pos);
// no need for DIV anymore
copyDiv.remove();
};
$(function (){
$('#scroll_button').click(
function() {
// scrolling to "FIND ME" using function written above
$('#txt').scrollToText('FIND ME');
return false;
}
);
});
Here is a demo (it works!): http://jsfiddle.net/KrVJP/
Since none of the answers actually solved the problem, I'll accept experimentX's one: thank you for putting an effort to help me, I appreciate it!
I am not sure if it will work. Please also check it here. It's seems working for 2000th, 1500th, and 1000th position.
EDIT confused font-size or line-height ???
$(function (){
var height = 2000/$('#txt').attr('cols');
$('#txt').scrollTop(height*13);
$('#txt').selectRange(2000,2000); //this is just to check
});
$.fn.selectRange = function(start, end) { //this is just to check
return this.each(function() {
if (this.setSelectionRange) {
this.focus();
this.setSelectionRange(start, end);
} else if (this.createTextRange) {
var range = this.createTextRange();
range.collapse(true);
range.moveEnd('character', end);
range.moveStart('character', start);
range.select();
}
});
};
UPDATE How about this one
var height = 1200/$('#txt').attr('cols');
var line_ht = $('#txt').css('line-height');
line_ht = line_ht.replace('px','');
height = height*line_ht;
You can use this jquery plugin
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