How to get the start and end points of selection in text area?
Revised answer, 5 September 2010
To account for trailing line breaks is tricky in IE, and I haven't seen any solution that does this. It is possible, however. The following is a new version of what I previously posted here.
Note that the textarea must have focus for this function to work properly in IE. If in doubt, call the textarea's focus()
method first.
function getInputSelection(el) {
var start = 0, end = 0, normalizedValue, range,
textInputRange, len, endRange;
if (typeof el.selectionStart == "number" && typeof el.selectionEnd == "number") {
start = el.selectionStart;
end = el.selectionEnd;
} else {
range = document.selection.createRange();
if (range && range.parentElement() == el) {
len = el.value.length;
normalizedValue = el.value.replace(/\r\n/g, "\n");
// Create a working TextRange that lives only in the input
textInputRange = el.createTextRange();
textInputRange.moveToBookmark(range.getBookmark());
// Check if the start and end of the selection are at the very end
// of the input, since moveStart/moveEnd doesn't return what we want
// in those cases
endRange = el.createTextRange();
endRange.collapse(false);
if (textInputRange.compareEndPoints("StartToEnd", endRange) > -1) {
start = end = len;
} else {
start = -textInputRange.moveStart("character", -len);
start += normalizedValue.slice(0, start).split("\n").length - 1;
if (textInputRange.compareEndPoints("EndToEnd", endRange) > -1) {
end = len;
} else {
end = -textInputRange.moveEnd("character", -len);
end += normalizedValue.slice(0, end).split("\n").length - 1;
}
}
}
}
return {
start: start,
end: end
};
}
Use the Rangy
api and all of your problems are gone gone
gone gone...
Using it
Read the documentation, or just use the below.
Very simple,
var selection = rangy.getSelection(), // Whole lot of information, supports
// multi-selections too.
start = selection.anchorOffset, // Start position
end = selection.focusOffset; // End position
Hope this api helps you out because it is really helpful in handling cross-browser ranges
.
I needed to do something very similar and came up with this:
function getSelection(target) {
var s = {start: 0, end:0};
if (typeof target.selectionStart == "number"
&& typeof target.selectionEnd == "number") {
// Firefox (and others)
s.start = target.selectionStart;
s.end = target.selectionEnd;
} else if (document.selection) {
// IE
var bookmark = document.selection.createRange().getBookmark();
var sel = target.createTextRange();
var bfr = sel.duplicate();
sel.moveToBookmark(bookmark);
bfr.setEndPoint("EndToStart", sel);
s.start = bfr.text.length;
s.end = s.start + sel.text.length;
}
return s;
}
Notes:
- The
sel
range must be created bytarget
rather than using the range returned bydocument.selection
, otherwisebfr.setEndPoint
will complain about an invalid argument. This "feature" (discovered in IE8) does not appear to be documented in the spec. -
target
must have input focus for this function to work. - Only tested with
<textarea>
, might work with<input>
as well.