autocomplete of words in the middle (jQuery UI) - jquery-ui

Question

Anyone know good sample code using jQuery UI's autocomplete widget that can autocomplete words in the middle of a text box, not just autocomplete of the word at the end only?
I'm using the jquery UI autocomplete widget for a component that supports entry of multiple tags. It's like like stack overflow's tag editor, but simpler: no fancy formatting in the autocomplete dropdown, no "tag" background images in the edit box. I started with the jQuery UI Autocomplete Multiple sample and modified it.
It's working OK, except autocomplete doesn't work for tags in the middle of a multi-tag string. For example, if I type C Fortran and then put the caret right after C and type +, I'd expect to see C++ in the autocomplete list but instead I see Fortran again.
Here's the code so far: http://jsfiddle.net/WCfyB/4/
This is the same problem described by autocomplete in middle of text (like Google Plus), but the problem in that question was simpler because he could rely on an empty # in the text to signal when to show the autocomplete. In my case, I can't just rely on the text-- I actually need to find out where the caret is and autocomplete for the word where the caret is.
I could build this myself using caret or another plugin, but was wondering if there was already a jQuery-UI-based sample online that I could use without re-inventing another wheel, especially if there are browser-specific corner cases to worry about. Ideally, it'd behave like this: whenever the user places the caret inside or at the end of a tag (where tags are always separated by 1+ spaces), autocomplete is shown for that tag. Know a good sample?

Answer 1

I don't know of any examples like this, but here's something that you could start with:
var availableTags = [ ... ];
function split(val) {
return val.split(/ \s*/);
}
function extractLast(term) {
return split(term).pop();
}
$("#tags")
.bind("keydown", function(event) {
// don't navigate away from the field on tab when selecting an item
if (event.keyCode === $.ui.keyCode.TAB
&& $(this).data("autocomplete").menu.active) {
event.preventDefault();
}
})
.autocomplete({
minLength: 0,
source: function(request, response) {
var results = [],
selectionStart = this.element[0].selectionStart
term = extractLast(request.term.substring(0, selectionStart));
if (term.length > 0) {
results = $.ui.autocomplete.filter(availableTags, term);
}
response(results);
},
focus: function() {
return false; // prevent value inserted on focus
},
select: function(event, ui) {
var terms = split(this.value.substring(0, this.selectionStart));
terms.pop(); // remove the current input
terms.push(ui.item.value); // add the selected item
this.value =
$.trim(terms.join(" ") + this.value.substring(this.selectionStart)) + " ";
return false;
}
});
Example: http://jsfiddle.net/WCfyB/7/
The major caveat here is that the selectionStart method does not work in IE. You can replace those function calls with one of those plugins you mentioned in your question.