jquery.caret.js

// Set caret position easily in jQuery
// Written by and Copyright of Luke Morton, 2011
// Licensed under MIT
(function ($) {
    // Behind the scenes method deals with browser
    // idiosyncrasies and such
    $.caretTo = function (el, index) {
        if (el.createTextRange) {
            var range = el.createTextRange();
            range.move("character", index);
            range.select();
        } else if (el.selectionStart != null) {
            el.focus();
            el.setSelectionRange(index, index);
        }
    };

    // Another behind the scenes that collects the
    // current caret position for an element

    // TODO: Get working with Opera
    $.caretPos = function (el) {
        if ("selection" in document) {
            var range = el.createTextRange();
            try {
                range.setEndPoint("EndToStart", document.selection.createRange());
            } catch (e) {
                // Catch IE failure here, return 0 like
                // other browsers
                return 0;
            }
            return range.text.length;
        } else if (el.selectionStart != null) {
            return el.selectionStart;
        }
    };

    // The following methods are queued under fx for more
    // flexibility when combining with $.fn.delay() and
    // jQuery effects.

    // Set caret to a particular index
    $.fn.caret = function (index, offset) {
        if (typeof(index) === "undefined") {
            return $.caretPos(this.get(0));
        }

        return this.queue(function (next) {
            if (isNaN(index)) {
                var i = $(this).val().indexOf(index);

                if (offset === true) {
                    i += index.length;
                } else if (typeof(offset) !== "undefined") {
                    i += offset;
                }

                $.caretTo(this, i);
            } else {
                $.caretTo(this, index);
            }

            next();
        });
    };

    // Set caret to beginning of an element
    $.fn.caretToStart = function () {
        return this.caret(0);
    };

    // Set caret to the end of an element
    $.fn.caretToEnd = function () {
        return this.queue(function (next) {
            $.caretTo(this, $(this).val().length);
            next();
        });
    };

    $.fn.insertAtCaret = function(myValue) {
        var obj;
        if( typeof this[0].name !='undefined' ) obj = this[0];
        else obj = this;

        if (document.selection) {
            obj.focus();
            sel = document.selection.createRange();
            sel.text = myValue;
            obj.focus();
        }
        else if (obj.selectionStart || obj.selectionStart == '0') {
            var startPos = obj.selectionStart;
            var endPos = obj.selectionEnd;
            var scrollTop = obj.scrollTop;
            obj.value = obj.value.substring(0, startPos)+myValue+obj.value.substring(endPos,obj.value.length);
            obj.focus();
            obj.selectionStart = startPos + myValue.length;
            obj.selectionEnd = startPos + myValue.length;
            obj.scrollTop = scrollTop;
        } else {
            obj.value += myValue;
            obj.focus();
        }
    };

    $.fn.replaceAtCaret = function(myValue) {
        var obj;
        if( typeof this[0].name !='undefined' ) obj = this[0];
        else obj = this;

        if (document.selection) {
            obj.focus();
            sel = document.selection.createRange();
            sel.text = myValue.replace('%%', sel);
            obj.focus();
        }
        else if (obj.selectionStart || obj.selectionStart == '0') {
            var startPos    = obj.selectionStart,
                endPos      = obj.selectionEnd,
                scrollTop   = obj.scrollTop,
                parts = [
                    obj.value.substring(0, startPos),
                    obj.value.substring(startPos, endPos),
                    obj.value.substring(endPos,obj.value.length)
                ];

            parts[1] = myValue.replace('%%', parts[1]);

            obj.value = parts.join('');
            obj.focus();
            obj.selectionStart  = startPos + myValue.length;
            obj.selectionEnd    = startPos + myValue.length;
            obj.scrollTop       = scrollTop;
        } else {
            obj.value += myValue;
            obj.focus();
        }
    };


}(jQuery));