jQuery insert text at caret

insertAtCaret.js

$.fn.extend({
    insertAtCaret: function(myValue) {
        var obj;
        if( typeof this[0].name !='undefined' ) obj = this[0];
        else obj = this;
        if ($.browser.msie) {
            obj.focus();
            sel = document.selection.createRange();
            sel.text = myValue;
            obj.focus();
        }else 
        if($.browser.mozilla || $.browser.webkit) {
            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();
        }
    }
});